BARLEY GENE FOR THIOREDOXIN AND NADP-THIOREDOXIN REDUCTASE

Abstract: The present invention provides barley thioredoxin h nucleic acids and NADP-thioredoxin reductase nucleic acids, the respective encoded proteins and methods of use.

Description: BARLEY GENE FOR THIOREDOXIN AND NADP-THIOREDOXIN REDUCTASE This application claims the benefit of the filing date of application Serial No. 60/127,198, filed March 31 , 1999 pending, application Serial No. 60/169,162, filed December 6, 1999, pending; application Serial No. 60/177,740 filed January 21 , 2000, pending; and application Serial No. 60/177,739, filed January 21, 2000, pending, all of which are expressly incorporated by reference in their entirety. ACKNOWLEDGMENT OF GOVERNMENT SUPPORT This invention was made with Government support under Grant 9803835 from the U.S. Department of Agriculture. The Government has certain rights to this invention. BACKGROUND OF THE INVENTION Thioredoxins are small (about 12 kDa) thermostable proteins with catalytically active disulfide groups. This class of proteins has been found in virtually all organisms, and has been implicated in myriad biochemical pathways (Buchanan et al., 1994). The active site of thioredoxin has two redox-active cysteine residues in a highly conserved amino acid sequence; when oxidized, these cysteines form a disulfide bridge (-S-S-) that can be reduced to the sulfhydryl (-SH) level through a variety of specific reactions. In physiological systems, this reduction may be accomplished by reduced ferredoxin, NADPH, or other associated thioredoxin-reducing agents. The reduced form of thioredoxin is an excellent catalyst for the reduction of even the most intractable disulfide bonds. Generally only one kind of thioredoxin is found in bacterial or animal cells. In contrast, photosynthetic organisms have three distinct types of thioredoxinrChloroplasts contain a ferredoxin/thioredoxin system comprised of ferredoxin, ferredoxin-thioredoxin reductase and thioredoxins fand m, which function in the light regulation of photosynthetic enzymes (Buchanan, 1991 ; Scheibe, 1991; Vogt et al, 1986). The other thioredoxin enzyme system is analogous to that established for animals and most microorganisms, in which thioredoxin (Λ-type in plants) is reduced by NADPH and NADPH-thioredoxin reductase (NTR) (Johnson et al., 1987a; Fiorencio et al., 1988; Suske et al., 1979). The reduction of thioredoxin h by this system can be illustrated by the following equation: NTR NADPH + H + + Thioredoxin h ox → NADP + Thioredoxin /7 red . Some plant species contain a family of closely related thioredoxin h proteins, which probably perform different physiological functions. Specific plants in which multiple thioredoxin h proteins have been found include spinach (Fiorencio et al., 1988), wheat (Johnson et at, 1987), rice (Ishiwatari et al., 1995), and Arabidopsis (Rivera-Madrid et al , 1995) The type-/? thioredoxin was discovered considerably after the discovery of the m and f types, and because of this much less is known about this cytoso c thioredoxin and its physiological functions Considerable work is currently directed toward studying thioredoxin h proteins (Besse and Buchanan, 1997) Thioredoxin h is widely distributed in plant tissues and exists in mitochondria, endoplasmic reticulum (ER) and the cytosol (Bodenstein-Lang etal , 1989, Marcus et al , 1991, Vogt et al 1986) Plant thioredoxin h is involved in a wide variety of biological functions Thioredoxin h functions in the reduction of intramolecular disulfide bridges of a variety of low molecular-weight, cystine-πch proteins, including thionins (Johnson et al , 1987b), pro t ease inhibitors and chloroform/methanol-soluble proteins (CM proteins) (Kobrehei et al , 1991) It is likely that cytoplasmic thioredoxins participate in developmental processes for example thioredoxin h has been shown, to function as a signal to enhance metabolic processes dunng germination and seedling development (Kobrehei et al , 1992, Lozano ef al , 1996, Besse et al , 1996) Thioredoxin h has also been demonstrated to be involved in self-incompatibility in Phalaπs coerulescens (Li ef al , 1995) and Brassica napus (Bower et al , 1996) Several functions have been hypothesized for rice thioredoxin h, which is believed to be involved in translocation in sieve tubes (Ishiwataπ et al , 1995) Uses of thioredoxin include incorporation into hair care products (U S Patent No 4,935,231) and neutralization of certain venoms and toxins (see U S Patent No 5,792,506) Recent research into thioredoxin activity has also focused on harnessing the reducing power of this protein for food technology For example, U S Patent No 5,792,506 to Buchanan (Neutralization of Food Allergens by Thioredoxin), and Buchanan et al (1998) describe the use of thioredoxin to reduce the allergeniαty of foods through thioredoxin-mediated reduction of intramolecular disulfide bonds found in various allergenic food proteins (e g , in milk, soya and wheat proteins) (Buchanan ef al , 1997, del Val ef a/ 1999) In addition, it has been shown that reduction of disulfide protein allergens in wheat and milk by thioredoxin decreases their allergeni ty (Buchanan ef al , 1997, del Val ef al , 1999) Thioredoxin treatment also increases the digestibility of the major allergen of milk (β-lactoglobulm) (del Val ef a/ , 1999), as well as other disulfide proteins (Lozano ef al , 1994, Jiao ef al , 1992) Thioredoxin h has been shown to be useful as a food additive to enhance the baking qualities of cereal flour (Bright ef al , 1983) For example, improvement in dough strength and bread quality properties of poor-quality wheat flour results from the addition of thioredoxin (Wong ef al , 1993, Kobrehei ef al , 1994) This has been attributable to the thioredoxm-catalyzed reduction of intramolecular disulfide bonds in the flour proteins, specifically the glutenins, resulting in the formation of new intermolecular disulfide bonds (Besse and Buchanan, 1997) Thus, the addition of exogenous thioredoxin promotes the formation of a protein network that produces flour with enhanced baking quality Kobrehei ef al , (1994) have observed that the addition of thioredoxin h to flour of non-glutenous cereals such as rice, maize and sorghum promotes the formation of a dough-like product Hence, the addition of exogenous thioredoxin may be used to produce baking dough from non-glutenous cereals cDNA clones encoding thioredoxin h have been isolated from a number of plant species, including Arabidopsis thaliana (Rivera-Madrid et al , 1993, Rivera-Madrid et al , 1995), Nicotiana tabacum (Marty and Meyer, 1991, Brugidou ef al , 1993), Or za sativa (Ishiwataπ ef al , 1995), Brassica napus (Bower ef al , 1996), Glycine max (Shi and Bhattacharyya, 1996), and Tnticum aestivum (Gautier ef al , 1998) Thioredoxin and NTR were first characterized in Escheπchia coli as the hydrogen donor system for nbonucleotide reductase (Laurent ef al , 1964- Moore ef al , 1964) The E coli NTR gene has been isolated (Russel and Model, 1988) and the three-dimensional structure of the protein has been analyzech(Kurιyan ef al , 1991) Some other NTR genes have been isolated and sequenced from bacteria, fungi and mammals Recently, Jacquot et al (1994) have reported a successful isolation and sequencing of two cDNAs encoding the plant Arabidopsis thaliana NTRs The subsequent expression of the recombinant A thaliana NTR protein in E coli cells (Jacquot et al , 1994) and its first eukaryotic structure (Dai et al , 1996) have also been reported Thioredoxin and NTR were first characterized in Escherichia coli as the hydrogen donor system for nbonucleotide reductase (Laurent et al , 1964, Moore ef al , 1964) The £ coli NTR gene has been isolated (Russel and Model, 1988) and the three-dimensional structure of the protein has been analyzed (Kuπyan et al , 1991) Some other NTR genes have been isolated and sequenced from bacteria, fungi, and mammals Recently, Jacquot ef al (1994) have reported a successful isolation and sequencing of two cDNAs encoding the plant Arabidopsis thaliana NTRs The subsequent expression of the recombinant A thaliana NTR protein in E coli cells (Jacquot et al , 1994) and its first eukaryotic structure (Dai et al , 1996) have also been reported Here we report isolated nucleic acids encoding the barley genes for thioredoxin h and NADP- thioredoxin reductase, isolated barley thioredoxin h and NADP-thioredoxin reductase proteins, and methods of use SUMMARY OF THE INVENTION The invention provides isolated nucleic acids encoding barley thioredoxin and NADP-thioredoxin reductase proteins and methods of use In other aspect the invention provides expression vectors comprising nucleic acids encoding barley thioredoxin and NADP-thioredoxin and transformed host cells Accordingly, the invention provides methods of expressing an isolated barley thioredoxin and NADP-thioredoxin reductase polypeptides In a further aspect the invention provides transgenic plants comprising the expression vectors In a preferred embodiment, the transgenic plants overexpress barley thioredoxin and NADP-thioredoxin reductase polypeptides The polypeptides of the invention, expressed in a transgenic plant either alone or in combination alters the redox status of a plant in comparison to a nontransgenic plant of the same species In a preferred embodiment, the expressed polypeptide transgene alters the redox status of a seed or grain, thereby altering the biochemical and biological properties of a seed or grain The seed or grain provides advantages in increased germination efficiency, decreased allergenicity, increased protein solubility, increased digestibility In another aspect, the invention provides methods of expressing a barley thioredoxin or NADP- thioredoxin reductase polypeptides In yet another aspect, the invention provides of expressing a barley thioredoxin or NADP-thioredoxin reductase polypeptide Accordingly, the invention provides isolated barley thioredoxin or NADP- thioredoxin reductase polypeptides In still yet another aspect the invention provides methods of identifying a bioactive agent that binds and preferably reduces a biological activity of a barley thioredoxin or NADP-thioredoxin reductase polypeptide BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a comparison of the ammo acid sequences of barley thioredoxin h and two wheat thioredoxin h proteins Figure 2 shows a comparison of the nucleic acid sequence encoding barley thioredoxin h and two wheat thioredoxin h molecules, and a consensus sequence derived by the comparison of these three sequences The BTRX/7 and wheat Trxh have about 90% sequence identity from positions 30-394 Figure 3 shows the positions of primers used for PCR amplification to isolate H vulgare NADP- thioredoxm reductase (NTR) Figure 4A-C shows the deduced ammo acid sequence of H vulgare NADP-thioredoxin reductase (NTR) and homologies Panel A shows the ammo acid sequence alignment of H vulgare NADP-thioredoxin reductase (NTR) and the NTR sequences of A thaliana and E coli Ammo acid identities are shown by shaded residues Panel B shows the percent similarity and percent divergence between ammo acid sequences of H vulgare NTR and the NTR sequences of A thaliana and £ coli Panel C shows the phylogenetic tree (in relative units) of H vulgare NTR and related sequences from A thaliana and £ coli Figure 5A-D shows the nucleotide sequence of H vulgare NADP-thioredoxin reductase (NTR) gene and homolgoies Panel A shows the nucleotide sequence alignment of H vulgare NTR gene and the NTR sequences of A thaliana and £ coli Nucleotides conserved in at least two out of three different NTR genes are shaded Panel B shows the nucleotide sequence alignment of H vulgare NTR gene and the NTR sequences of A thaliana and £ coli Nucleotides conserved nucleotides the three different NTR genes are shaded Panel C shows the percent homology and percent divergence between nucleotide sequences of H vulgare NTR and the NTR sequences of A thaliana and £ coli Panel D shows that the phylogenetic tree (in relative units) of H vulgare NTR and related nucleotide sequences from A thaliana and £ coli Figure 6 shows the thioredoxin h constructs used for transformation Figure 7 shows the thioredoxin activity profile of various barley grains transformed with wheat thioredoxin gene {vήrxh) Figure 8 shows the effects of heat treatment on thioredoxin activity of crude extracts from barley grains Figure 9A-B shows a western blot analysis of extract from segregating T, barley gram of stable transformants containing wtnch Panel A lanes 1 and 6, control barley extract (cv Golden Promise), lane 2, bread wheat extract {Tπticum aestivum, cv Capitole), lane 3, extract from GPdBhss BarWtrx 22, lane 4, extract from GPdBhssBarWtrx 29, lane 5, extract from GPdBhBarWtrx 2 Panel B lane 1 , GPdBhBaarWtrx 2, lane 2 control barley extract W, wheat, B, barley Figure 10 shows western blot analysis of extracts of T, T 2 and T 3 barley grain transformed with wtrxh Forty micrograms of soluble proteins extracted from 10-20 grains of each line were fractionated by SDS/PAGE Lane 1 , wheat germ thioredoxin h, lane 2, nontransgenic control of GP4-96, lane 3, null segregant T 2 grain of GPdBhssBarWtrx-29-11-10, lane 4, heterozygous T, grain of GPdBhssBarWtrx- 29, lane 5, homozygous T 2 grain of GPdBhssBarWtrx-29-3, lane 6, homozygous T 2 grain of GPdBhssBarWtrx-29-3-2, lane 7, prestamed standards (aprotinm, 9 kDa, lysozyme, 17 8 kDa, soybean trypsin inhibitor, 30 6kDa, carbonic anhydrase, 41 8 kDa, BSA, 71 kDa) Figure 11 shows the nucleic acid sequence of the promoter and the 57 base pair B 1 -hordeιn signal sequence (underlined) Figure 12 shows the nucleic acid sequence of the D-hordein promoter and the 63 base pair D-hordein signal sequence (underlined) Figure 13A-C shows the effect of overexpressed thioredoxin h on pullulanase activity in transgenic barley gram during germination and seedling development A homozygous line, GPdBhssBarWtrx-29- 3, and a null segregant, GPdBhssBarWtrx-29-11-10, were used for the pullulanase assays Panel A Pullulanase was assayed spectrophotometπcaily by measuring the dye released from red pullulan substrate at 534 nm Panel B Pullulanase was separated on native 7 5% polyacrylamide gels containing the red pullulan substrate Activity, identified by comparison with purified barley pullulanase, is seen as clear areas that developed on incubating the gel in 0 2 M succmate buffer, pH 6 0, for 1 hr at 37°C Panel C The gel in Panel B was scanned and analyzed by integration of the activity bands Figure 14A-D shows the change in t!ιe activity and abundance of amylases in transgenic and null segregant barley grains during germination and seedling development based on an activity gel Panel A abundance of alpha-amylases in null segregant based on westerrrblot Panel B Total amylase activity in null segregant Panel C abundance of alpha-amylases in thioredoxin overexpressmg grains Panel D total amylase activity in thioredoxin overexpressed grains Figure 15 shows the effect of overexpressed thioredoxin h on the activity of the major form of alpha- amylase during germination and seeding development The size of the major alpha-amylase activity band in Figure 14 was estimated by its rate of mobility during electrophoresis Figure 16A-B shows the effect of overexpressed thioredoxin h on the abundance of alpha-amylase A and B isozymes during germination and seedling development The figure represents western blots of IEF gels developed for the null segregant and transgenic barley grains Panel A Null segregant Panel B Transgenic with thioredoxin overexpressed Figure 17 shows the effect of overexpressed wheat thioredoxin h on the germination of null segregant and transgenic (homozygous) barley grains Figure 18 shows the relative redox status of protein fractions in transgenic barley gram overexpressmg wheat thioredoxin h in comparison to the null segregant in dry and germination grain SEQUENCE LISTING The nucleic and ammo acid sequences listed in the accompanying sequence listing (SEQ ID NO 1-24) are shown using standard letter abbreviations for nucleotide bases, and three letter code for ammo acids Only one strand of each nucleic acid sequence is shown, but it is understood that the complementary strand is included by any reference to the displayed strand SEQ ID NO 1 shows the nucleic acid sequence of the barley thioredoxin h cDNA SEQ ID NO 2 shows the ammo acid sequence of the barley thioredoxin h protein SEQ ID NO 3 shows the nucleic acid sequence of a wheat thioredoxin h cDNA, GenBank accession number X699 15 SEQ ID NO 4 shows the ammo acid sequence of a wheat thioredoxin h protein SEQ ID NO 5 shows the nucleic acid sequence of a wheat thioredoxin h cDNA, GenBank accession number AJ00 1903 SEQ ID NO 6 shows the ammo acid sequence of a wheat thioredoxin h protein SEQ ID NO 11 shows the nucleic acid sequence of the barley B^hordem promoter and signal sequence SEQ ID NO 12 shows the nucleic acid sequence of the barley D-hordein promoter and signal sequence Other SEQ ID NOs are described herein DETAILED DESCRIPTION OF THE INVENTION I. Definitions Unless otherwise noted, technical terms are used according to conventional usage Definitions of common terms in molecular biology may be found in Lewin, Genes V published by Oxford University Press, 1994 (ISBN 0-19-854287-9), Kendrew et al (eds ), The Encyclopedia of Molecular Biology, published by Blackwell Science Ltd , 1994 (ISBN 0-632-02182-9), and Robert A Meyers (ed ), Molecular Biology and Biotechnology a Comprehensive Desk Reference, published by VCH Publishers, Ine , 1995 (ISBN 1-56081-569-8), Ausubel et al (1987) Current Protocols in Molecular Biology, Green Publishing, Sambrook ef al (1989) Molecular Cloning A Laboratory Manual, Cold Spring Harbor, New York) In order to facilitate review of the various embodiments of the invention, the following definitions are provided Thioredoxin protein: A large number of plant, animal, and microbial thioredoxin proteins have been characterized, and the genes encoding many of these proteins have been cloned and sequenced The present invention is preferably directed to the use of thioredoxin h proteins, although other thioredoxin proteins may also be employed to produce transgenic plants as described herein Among the thioredoxin h proteins from plants that have been described to date are thioredoxin h proteins from Arabidopsis thaliana (Rivera-Madrid ef al , 1993, Rivera-Madrid et al , 1995), Nicotiana tabacum (Marty and Meyer, 1991, Brugidou ef al , 1993), Oryza sativa (Ishiwataπ ef a/ , 1995), Brassica napus (Bower ef al , 1996), Glycine max (Shi and Bhattacharyya, 1996), and Tnticum aestivum (Gautier ef al , 1998) The ammo acid sequences of these and other thioredoxin h proteins, and the nucleotide sequence of cDNAs and/or genes that encode these proteins, are available in the scientific literature and publicly accessible sequence databases For example, a cDNA encoding thioredoxin h from Picea manana is described in accession number AF051206 (NID g2982246) of GenBank, and located by a search using the Entrez browser/ nucleotide sequence search of the National Center for Biotechnology Information website, www ncbi nlm nih gov The cDNA encoding the Tnticum aestivum thioredoxin h protein used in the Examples described below is described on the same database under accession number X69915 (NID g2995377) The present invention may be practiced using nucleic acid sequences that encode full length thioredoxin h proteins, as well as thioredoxin h derived proteins that retain thioredoxin h activity Thioredoxin h derived proteins which retain thioredoxin biological activity include fragments of thioredoxin h, generated either by chemical (e g enzymatic) digestion or genetic engineering means, chemically functionalized protein molecules obtained starting with the exemplified protein or nucleic acid sequences, and protein sequence variants Thus, the term "thioredoxin h protein" encompasses full length thioredoxin h proteins, as well as such thioredoxin h denveti proteins that retain thioredoxin h activity Thioredoxin protein may be quantified in biological samples (such as seeds) either in terms of protein level, or in terms of thioredoxin activity Thioredoxin protein level may be determined using a western blot analysis followed by quantitative scanning of the image as described in detail below Thioredoxin activity may be quantified using a number of different methods known in the art Preferred methods of measuring thioredoxin biological activity attributable to thioredoxin π in plant extracts include NADP/malate dehydrogenase activation (Johnson etal , 1987a,b) and reduction of 2',5'-dιthιobιs(2-nιtrobenzoιc acid) (DTNB) via NADP-thioredoxin reductase (Fiorencio ef al , 1988, U S Patent No 5,792,506) Due to the potential for interference from non-thioredox h enzymes that use NADPH, accurate determination of thioredoxin h activity should preferably be made using partially punfied plant extracts. Standard protein purification methods (e g (NH 4 ) 2 S0 4 extraction) can be used to accomplish this partial purification The activity of thioredoxin h may also be expressed in terms of specific activity, i e , thioredoxin activity per unit of protein present, as described in more detail below Probes and primers: Nucleic acid probes and primers may readily be prepared based on the hucleic acids provided by this invention A probe comprises an isolated nucleic acid attached to a detectable label or reporter molecule Typical labels include radioactive isotopes, ligands, chemiiummescent agents, and enzymes Methods for labeling and guidance in the choice of labels appropriate for various purposes are discussed, e g , in Sambrook ef al (1989) and Ausubel ef al (1987) Primers are short nucleic acids, preferably DNA oligonucleotides about 15 nucleotides or more in length Primers may be annealed to a complementary target DNA strand by nucleic acid hybridization to form a hybrid between the primer and the target DNA strand, and then extended along the target DNA strand by a DNA polymerase enzyme Primer pairs can be used for amplification of a nucleic acid sequence, e g, by the polymerase chain reaction (PCR) or other nucleic-acid amplification methods known in the art Methods for preparing and using probes and primers are described, for example, in Sambrook ef al (1989), Ausubel ef al (1987), and Innis ef al , (1990) PCR primer pairs can be derived from a known sequence, for example, by using computer programs intended for that purpose such as Primer (Version 0 5, © 1991 , Whitehead Institute for Biomedical Research, Cambridge, MA) One of skill in the art will appreciate that the specificity of a particular probe or primer increases with its length Thus, for example, a primer comprising 20 consecutive nucleotides of the barley thioredoxin h cDNA will anneal to a target sequence such as a thioredoxin h homologue from a different barley cultivar contained within a cDNA or genomic DNA library with a Higher specificity than a corresponding primer of cnly 15 nucleotides Thus, in order to obtain greater specificity, probes and primers may be selected that comprise 20, 25, 30, 35, 40, 50 or more consecutive nucleotides of the barley thioredoxin h cDNA or gene sequences Accordingly, oligonucleotides that are derived from the barley thioredoxin h and NTR nucleic acids are encompassed within the scope of the present invention Preferably, such oligonucleotide primers will comprise a sequence of at least 15-20 consecutive nucleotides of the barley thioredoxin h encoding sequences Promoter: A regulatory nucleic acid sequence, typically located upstream (5') of a gene that, in conjunction with various cellular proteins, is responsible for regulating the expression of the gene Promoters may regulate gene expression in a number of ways For example, the expression may be tissue-specific, meaning that the gene is expressed at enhanced levels in certain tissues, or developmentally regulated, such that the gene is expressed at enhanced levels at certain times during development, or both In a preferred embodiment, artransgene of the invention is expressed in an edible part of a plant By "edible" herein is meant at least a part of a plant that is suitable for consumption by humans or animals (fish, crustaceans, isopods, decapods, monkeys, cows, goats, pigs, rabbits, horses, birds (chickens, parrots etc) Accordingly, "edible" embraces food for human consumption and feed for animal consumption and includes, for example, dough, bread, cookies, pasta, pastry, beverages, beer, food additives, thickeners, malt, extracts made from an edible part of plants, animals feeds, and the like An edible part of a plant includes for example, a root, a tuber, a seed, gram, a flower, fruit, leaf etc The skilled artisan is aware that expression of the transgene is effected in any tissue, organ or part of a plant by employing a promoter that is active in the selected part of the plant the transgene is to be expressed In a preferred embodiment the transgene is expressed in a seed, preferably under control of a seed- or gram-specific promoter The expression of a transgene in seeds or grains according to the present invention is preferably accomplished by operably linking a seed-specific or gram-specific promoter to the nucleic acid molecule encoding the transgene protein In this context, "seed-specific" indicates that the promoter has enhanced activity in seeds compared to other plant tissues, it does not require that the promoter is solely active in the seeds Accordingly, "gram-specific" indicates that the promoter has enhanced activity in grains compared to other plant tissues, it does not require that the promoter is solely active in the grain Preferably, the seed- or grain-specific promoter selected will, at the time when the promoter is most active in seeds, produce expression of a protein in the seed of a plant that is at least about two-fold greater than expression of the protein produced by that same promoter in the leaves or roots of the plant However, given the nature of the thioredoxin protein, it may be advantageous to select a seed- or grain-specific promoter that causes little or no protein expression in tissues other than seed or grain In a preferred embodiment, a promoter is specific for seed and gram expression, such that, expression in the seed and grain is enhanced as compared to other plant tissues but does not require that the promoter be solely activity in the grain and seed In a preferred embodiment, the promoter is "specific" for a structure or element of a seed or grain, such as an embryo-specific promoter In accordance with the definitions provided above, an embryo-specific promoter has enhanced activity in an embryo as compared to other parts of a seed or gram or a plant and does not require its activity to be limited to an embryo In a preferred embodiment, the promoter is "maturation- specific" and accordingly has enhanced activity developmentally during the maturation of a part of a plant as compared to other parts of a plant and does not require its activity to be limited to the development of a part of a plant A seed- or gram-specific promoter may produce expression in various tissues of the seed, including the endosperm, embryo, and aleurone or gram Any seed- or grain-specific promoter may be used for this purpose, although it will be advantageous to select a seed- or gram-specific promoter that produces high level expression of the protein in the plant seed or grain Known seed- or gram-specific promoters include those associated with genes that encode plant seed storage proteins such as genes encoding barley hordems, rice glutenns, oryzms, or prolamines, wheat gliadms or glutenins, maize zeins or glutelins, maize embryo-specific promoter, oat glutelms, sorghum kafinns, millet pennisetins, or rye secalms The barley hordein promoters (described in more detail below) are seed- or gram-specific promoters that were used in the illustrative Examples (Cameron-Mills, 1980, Cameron-Mills et al , 1980, 1988a,b) In certain embodiments, the seed- or grain-specific promoter that is selected is a maturation-specific promoter The use of promoters that confer enhanced expression during seed or grain maturation (such as the barley hordein promoters) may result in even higher levels of thioredoxin expression in the seed By "seed or gram-maturation" herein refers to the period starting with fertilization in which metabo zable food reserves (e g , proteins, lipids, starch, efc ) are deposited in the developing seed, particularly in storage organs of the seed, including the endosperm, testa, aleurone layer, embryo, and scutellar epithelium, resulting in enlargement and filling of the seed and ending with seed desiccation Members of the grass family, which include the cereal grains, produce dry, one-seeded fruits This type of fruit, is strictly speaking, a caryopsis but is commonly called a kernel or gram The caryopsis of a fruit coat or pericarp, which surrounds the seed and adhere tightly to a seed coat The seed consists of an embryo or germ and an endosperm enclosed by a nucellar epidermis and a seed coat Accordingly the grain comprises the seed and its coat or pericarp The seed comprises the embryo and the endosperm (R Carl Hoseney in "Principles of Cereal Science and Technology", expressly incorporated by reference in its entirety) Starch: A polysacchande made up of a chain of glucose units joined by alpha-1 ,4 linkages, either unbranched (amyiose) or branched (amylopectm) at alpha-1 ,6-lιnkages Dextran: Any of a variety of storage polysacchandes, usually branched, made of glucose residues joined by alpha-1 ,6 linkages Dextrin or Limit Dextrin: Any of a group of small soluble polysacchandes, partial hydrolysis products of starch, usually enriched in alpha-1 ,6-lιnkages Germination: A resumption of growth of a plant embryo in favorable conditions after seed maturation and drying (dessication), and emergence of young shoot and root from the seed Allergen: An antigenic substance that induces an allergic reaction in a susceptible host Accordingly, a susceptible host has an immune status (hypersensitivity) that results in an abnormal or harmful immune reaction upon exposure to an allergen In a preferred embodiment, the transgenic grains of the invention have reduced allergenicity in comparison to nontransgenic grains The immune reaction can be immediate or delayed, cell mediated or antibody mediated, or a combination thereof In a preferred embodiment, the allergic reaction is an immediate type hypersensitivity Digestion: By "digestion" herein is meant the conversion of a molecule or compound to one or more of its components Accordingly, "digestibility" relates to the rate and efficiency at which the conversion to one or more of its components occurs In a preferred embodiment a "digestible compound" is, for example, a food, that is converted to its chemical components by chemical or enzymatic means For example, dextran is converted to dextrin, polysacchaπde, monosacchandes, limit dextrin etc, a protein is converted to a polypeptides, oligopeptides, ammo acids, ammonia etc , a nucleic acid is converted to oligonucleotides, nucleotides, nucleosides, puπne, pyπmidines, phosphates etc In a preferred embodiment, the transgenic grains of the invention have increased digestibility, i e are more efficiently or rapidly digested in comparison to nontransgenic grain Germination: A resumption of growth of a plant embryo in favorable conditions after seed or grain maturation and drying (dessication), and emergence of young shoot and root from the seed or gram Vector: A nucleic -cid molecule as introduced into a host cell, thereby producing a transformed host cell A vector may include one or more nucleic acid sequences that permit it to replicate in one or more host cells, such as orιgιn(s) of replication A vector may also include one or more selectable marker genes and other genetic elements known in the art Transformed: A transformed cell is a cell into which has been introduced a nucleic acid molecule by molecular biology techniques As used herein, the term transformation encompasses all techniques by which a nucleic acid molecule might be introduced into such a cell, plant or animal cell, including transfection with viral vectors, transformation by Agrobactenum, with plasmid vectors, and introduction of naked DNA by electroporation, lipofection, and particle gun acceleration and includes transient as well as stable transformants Isolated: An "isolated" biological component (such as a nucleic acid or protein or organelle) has been substantially separated or purified away from other biological components in the cell or the organism in which the component naturally occurs, i e , other chromosomal and extra-chromosomal DNA and RNA, proteins and organelles Nucleic acids and proteins that have been "isolated" include nucleic acids and proteins purified by standard puπfication methods The term embraces nucleic acids including chemιcal<y synthesized nucleic acids and also embraces proteins prepared by recombinant expression in vitro or in a host cell and recombinant nucleic acids as defined below Operably linked: A first nucleic acid sequence is operably linked with a second nucleic acid sequence when the first nucleic acid sequence is placed in a functional relationship with the second nucleic acid sequence For instance, a promoter is operably linked to a coding sequence if the promoter affects the transcription or expression of the coding sequence Generally, operably linked DNA sequences are contiguous and, where necessary, join two protein-coding regions in the same reading frame With respect to polypeptides, two polypeptide sequences may be operably linked by covalent linkage, such as through peptide bonds or disulfide bonds Recombinant: By "recombinant nucleic acid" herein is meant a nucleic acid that has a sequence that is not naturally occurring or has a sequence that is made by an artificial combination of two otherwise separated segments of sequence This artificial combination is often accomplished by chemical synthesis or, more commonly, by the artificial manipulation of of nucleic acids, e g , by genetic engineering techniques, such as by the manipulation of at least one nucleic acid by a restriction enzyme, ligase, recombinase, and/or a polymerase Once introduced into a host cell, a recombinant nucleic acid is replicated by the host cell, however, the recombinant nucleic acid once replicated in the cell remains a recombinant nucleic acid for purposes of this invention By "recombinant protein" herein is meant a protein produced by a method employing a recombinant nucleic acid As outlined above "recombinant nucleic acids" and "recombinant proteins" also are "isolated", as described above Complementary DNA (cDNA): A piece of DNA that is synthesized in the laboratory by reverse transcπption of an RNA, preferably an RNA extracted from cells cDNA produced from mRNA typically lacks internal, non-coding segments (introns) and regulatory sequences that determine transcription Open reading frame (ORF): A series of nucleotide triplets (codons) coding for ammo acids without any internal termination codons These sequences are usually translatable into a peptide Transgenic plant: As used herein, this term refers to a plant that contains recombinant or isolated genetic matenal not normally found in plants of this type and which has been introduced into the plant in question (or into progenitors of the plant) by human manipulation Thus, a plant that is grown from a plant cell into which recombinant DNA is introduced by transformation is a transgenic plant, as are all offspπng of that plant that contain the introduced transgene (whether produced sexually or asexuaily) It is understood that the term transgenic plant encompasses the entire plant and parts of said plant, for instance grains, seeds, flowers, leaves, roots, fruit, pollen, stems efc The present invention is applicable to both dicotyledonous plants ( e g tomato, potato, soybean, cotton, tobacco, etc ) and monocotyledonous plants, including, but not limited to graminaceous monocots such as wheat (Tπticum spp ), rice {Oryza spp ), barley (Hordeum spp ), oat {Avena spp ), rye (Seca/e spp ), corn {Zea mays), sorghum {Sorghum spp ) and millet (Penmsetum spp) For example, the present invention can be employed with barley genotypes including, but not limited to Morex, Harrington , Crystal, Stander, Moravian III, Galena, Salome, Steptoe, Klages, Baronesse, and with wheat genotypes including, but not limited to Yecora Rojo, Bobwhite, Karl and Anza In general, the invention is particularly useful in cereals Purified: The term purified does not require absolute purity, rather, it is intended as a relative term Thus, for example, a purified barley thioredoxin h protein preparation is one in which the barley thioredoxin h protein is more enriched or more biochemically active or more easily detected than the protein is in its natural environment within a cell or plant tissue Accordingly, "purified" embraces or includes the removal or inactivation of an inhibitor of a molecule of interest In a preferred embodiment, a preparation of barley thioredoxin h protein is purified such that the barley thioredoxin h represents at least 5-10% of the total protein content of the preparation For particular applications, higher protein purity may be desired, such that preparations in which barley thioredoxin t? represents at least 50% or at least 75% or at least 90% of the total protein content may be employed Ortholog: Two nucleotide or ammo acid sequences are orthologs of each other if they share a common ancestral sequence and diverged when a species carrying that ancestral sequence split into two species, sub-species, or cultivars Orthologous sequences are also homologous sequences II. Thioredoxin h (BTRXft) and NADP-thioredoxin Reductase (NTR) from Barley (Hordeum vulgare L.) Herein are provided BTRXt? and NTR proteins and nucleic acids which encode such proteins Also provided are methods of screening for a bioactive agent capable of binding and preferably modulating the activity of the BTRXΛ or NTR protein The method comprises combining a BTRX/? or an NTR protein and a candidate bioactive agent and a cell or a population of cells, and determining the effect on the cell in the presence and absence of the candidate agent Other screening assays including binding assays are also provided herein as described below NTR belongs to the pyπdine nucleotide-disulfide oxidoreductase family (Pai, 1991), which includes glutathione reductase, lipoamide dehydrogenase, mercuric reductase and trypanothionme reductase, which catalyze the transfer of electrons from a pyπdine nucleotide via a flavin carrier to, in most cases, disulfide-containing substrates Preferably, NTR is barley H vulgare NTR and is a flavoenzyme that reduces thioredoxin h using NADPH We have found that barley NTR reduces wheat thioredoxin h (Cho ef a/ 1999 (PNAS)) A barley thioredoxin protein is a bariey protein having thioredoxin biological activity Plant thioredoxins are generally categorized into three subgroups (m, f, and h) based on subcellular localization and specificity of enzyme activation A barley thioredoxin h (BTRXΛ) protein is a barley protein having thioredoxin protein biological activity and sharing ammo acid sequence identity and/or is encoded by a nucleic acid that hybridizes under high stπngency conditions to the exemplified BTRXΛ nucleic acid as described below Thioredoxin proteins typically contain a consensus active site - WCGPC (residues 45-49 of SEQ ID NO 2) Though it is not absolutely required in general thioredoxin proteins can also be identified by the presence of this or a similar sequence A BTRXfi and an NTR protein of the present invention also may be identified in alternative ways "Protein" in this sense includes proteins, polypeptides, and peptides The BTRX/7 and NTR proteins of the invention fail into two general classes proteins that are completely novel, i e are not part of a public database as of the time of discovery, although they may have homology to either known proteins or peptides encoded by expressed sequence tags (ESTs) and the like Alternatively, the BTRXΛ and NTR proteins are known proteins, but that were not known to be, respectively, thioredoxins or oxidoreductases that preferably reduce thioredoxin h Accordingly, a NTR protein may be initially identified by its association with a protein known to be involved in the reduction of thioredoxin A BTRXft protein may be initially identified by its association with an NTR protein Wherein the BTRXn and NTR proteins and nucleic acids are novel, compositions and methods of use are provided herein In the case that the BTRXf? and NTR proteins and nucleic acids were known but not known to be thioredoxins or oxidoreductases that preferably reduce thioredoxin h, methods of use, i e functional screens, are provided In one embodiment, a BTRXΛ or an NTR protein as defined herein has at least one of the following "BTRX/i biological activities or "NTR biological activities" By "NTR biological activity" herein preferably is meant the catalytic reduction of thioredoxin coupled to NADPH 2 oxidation By "thioredoxin protein biological activity" herein is meant the ability of a protein to serve as a hydrogen donor in various reduction reactions (Smith ef al (eds ) 1997) One of ordinary skill in the art will be aware that there are many well-established systems that can be employed to measure thioredoxin mediated reduction reactions Preferred methods of measuring biological thioredoxin activity attributable to thioredoxin h include NADP/malate dehydrogenase activation (Johnson ef al , 1987) and reduction of 2',5'-dιthιobιs(2-nιtrobenzoιc acid) (DTNB) via NADP-thioredoxin reductase (Fiorencio ef al , 1988, U S Patent No 5,792,506) Due to the potential for interference from non-thioredoxin h enzymes that use NADPH, accurate determination of thioredoxin h activity should be made using partially purified plant extracts Standard protein purification methods (e g (NH 4 ) 2 S0 4 extraction and acid fractionation) can be used to accomplish this partial purification, as discussed more fully below In one embodiment provided herein, BTRXf? and an NTR protein as defined herein have sequence homology to other thioredoxin and NTR proteins, respectively By "homology" herein is meant sequence similarity and identity, with identity being preferred In one embodiment, the homology is found using the following database, algorithm, and parameters The similarity between two nucleic acid sequences, or two am o acid sequences is expressed in terms of sequence identity (or, for proteins, also in terms of sequence similarity) Sequence identity is frequently measured in terms of percentage identity, the higher the percentage, the more similar the two sequences are As described above, homologs and variants of the thioredoxin nucleic acid molecules, hordein promoters and hordein signal peptides may be used in the present invention Homologs and vaπants of these nucleic acid molecules will possess a relatively high degree of sequence identity when aligned using standard methods Methods of alignment of sequences for comparison are well known in the art Various programs and alignment algorithms are descnbed in Smith and Waterman (1981), Needleman and Wunsch (1970), Pearson and Lipman (1988), Higgms and Sharp (1988), Higgins and Sharp (1989), Corpet ef al , (1988), Huang et al , (1992), and Pearson ef a/ , (1994) Altschul et al , (1994) presents a detailed consideration of sequence alignment methods and homology calculations The NCBI Basic Local Alignment Search Tool (BLAST) (Altschul ef al , 1990) is available from several sources, including the National Center for Biotechnology Information (NCBI, Bethesda, MD) and on the Internet, for use in connection with the sequence analysis programs blastp, blastn, blastx, tblastn and tblastx It can be accessed at http //www ncbi nlm nih gov/BLAST A description of how to determine sequence identity using this program is available at http //www nchi nlm nih qov/BLAST/blast help html Homologs of the disclosed protein sequences are typically characterized by possession of at least 40% sequence identity counted over the full length alignment with the am o acid sequence of the disclosed sequence using the NCBI Blast 2 0, gapped blastp set to default parameters The adjustable parameters are preferably set with the following values overlap span =1 , overlap fraction = 0 125, word threshold (T) = 11 The HSP S and HSP S2 parameters are dynamic values and are established by the program itself depending upon the composition of the particular sequence and composition of the particular database against which the sequence of interest is being searched, however, the values may be adjusted to increase sensitivity Proteins with even greater similarity to the reference sequences will show increasing percentage identities when assessed by this method, such as at least about 50%, at least about 60%, at least about 70%, at least about 75%, at least about 80%, at least about 90% or at least about 95% sequence identity Homologs of the disclosed nucleic acid sequences are typically characterized by possession of at least 40% sequence identity counted over the full length alignment with the ammo acid sequence of the disclosed sequence using the NCBI Blast 2 0, gapped blastn set to default parameters A preferred method utilizes the BLASTN module of WU-BLAST-2 (Altschul ef al , 1996), set to the default parameters, with overlap span and overlap fraction set to 1 and 0 125, respectively Nucleic acid sequences with even greater similarity to the reference sequences will show increasing percentage identities when assessed by this method, such as at least about 50%, at least about 60%, at least about 70%, at least about 75%, at least about 80%, at least about 90% or at least about 95% sequence identity The alignment may include the introduction of gaps in the sequences to be aligned In addition, for sequences which contain either more or fewer ammo acids than the protein encoded by the sequences in the figures, it is understood that in one embodiment, the percentage of sequence identity will be determined based on the number of identical ammo acids in relation to the total number of ammo acids Thus, for example, sequence identity of sequences shorter than that shown in the figures as discussed below, will be determined using the number of ammo acids in the longer sequence, in one embodiment In percent identity calculations relative weight is not assigned to vanous manifestations of sequence variation, such as, insertions, deletions, substitutions, efc In one embodiment, only identities are scored positively (+1) and all forms of sequence variation including gaps are assigned a value of "0", which obviates the need for a weighted scale or parameters as described herein for sequence similarity calculations Percent sequence identity can be calculated, for example, by dividing the number of matching identical residues by the total number of residues of the "shorter" sequence in the aligned region and multiplying by 100 The "longer" sequence is the one having the most actual residues in the aligned region This method of sequence identity can be applied in the analysis of ammo acid and nucleic acid sequences As will be appreciated by those skilled in the art, the sequences of the present invention may contain sequencing errors That is, there may be incorrect nucleosides, frameshifts, unknown nucleosides, or other types of sequencing errors in any of the sequences, however, the correct sequences will fall within the homology and stringency definitions herein The alignment tools ALIGN (Myers and Miller, 1989) or LFASTA (Pearson and Lipman, 1988) may be used to perform sequence comparisons (Internet Program © 1996, W R Pearson and the University of Virginia, "fasta20u63" version 2 0u63, release date December 1996) ALIGN compares entire sequenceε against one another, while LFASTA compares regions of local similarity These alignment tools and their respective tutorials are available on the internet at http //biology ncsa uiuc edu In a preferred embodiment, orthologs of the disclosed barley thioredoxin h protein are typically characterized by possession of greater than 90 6% sequence identity counted over the full-length alignment with the ammo acid sequence of barley thioredoxin h using ALIGN set to default parameters Proteins with even greater similarity to the reference sequences will show increasing percentage identities when assessed by this method, such as at least 92%, at least 93%, at least 95%, at least 96%, at least 97%, or at least 98% sequence identity When less than the entire sequence is being compared for sequence identity, homologs will typically possess at least 90% sequence identity over short windows of 10-20 ammo acids, and may possess sequence identities of at least 93%, at least 95%, at least 97%, or at least 99% depending on their similarity to the reference sequence Sequence identity over such short windows can be determined using LFASTA, methods are descπbed at http //biology ncsa uiuc edu One of skill in the art will appreciate that these sequence identity ranges are provided for guidance only, it is entirely possible that strongly significant homologs could be obtained that fall outside of the ranges provided The present invention provides not only the peptide homologs that are described above, but also nucleic acid molecules that encode such homologs In a preferred embodiment, members of a thioredoxin h protein family having thioredoxin protein biological activity sharing ammo acid sequence identity with the ammo acid sequence of the prototypical barley thioredoxin h protein shown in SEQ ID NO 2 In a preferred embodiment, BTRX/7 proteins of the invention will generally share greater than 90 2% ammo acid sequence identity with the sequence shown in SEQ ID NO 2, as determined using ALIGN set to'default parameters More closely related thioredoxin proteins may share at least 92%, 95%, or 98% sequence identity with the exemplified BTRXti protein In a preferred embodiment, a protein is a "NTR protein" as defined herein if the overall sequence identity of the am o acid sequence of Figure 4A (SEQ ID NO 9) is preferably greater than about 71 %, more preferably greater than about 85%, even more preferably greater than about 90% and most preferably greater than 95% In some embodiments the sequence identity will be as high as about 98% and higher Barley thioredoxin h derived proteins and NTR derived proteins include fragments, respectively of thioredoxin h or NTR, generated either by chemical (e g enzymatic) digestion or genetic engineering means, chemically functionalized protein molecules obtained starting with disclosed protein or nucleic acid sequences, and protein sequence variants, which retain measurable thioredoxin h protein biological activity For example, while the prototypical barley thioredoxin h protein shown in SEQ ID NO 2 is 122 ammo acids in length, one of skill in the art will appreciate that thioredoxin biological activity may be obtained using a protein that comprises less than the full length barley thioredoxin h protein Thus the terms "barley thioredoxin h protein" and "barley NTR protein" includes fragments, respectively, of a full length barley thioredoxin h protein, which fragments retain thioredoxin protein biological activity or NTR protein biological activity, and variants, such as, naturally occurring allelic variants and mutants obtained by in vitro mutagenesis techniques and the like as further described below In one embodiment, BTRXti and NTR nucleic acids or BTRXti and NTR proteins are initially identified by substantial nucleic acid and/or ammo acid sequence identity or similarity to the sequence(s) provided herein In a preferred embodiment, BTRXft or NTR nucleic acids or Brtxh or NTR proteins have sequence identity or similarity to the sequences provided herein and one or more of their respective "biological activities" Such sequence identity or similarity can be based upon the overall nucleic acid or ammo acid sequence The BTRXft and NTR proteins of the present invention may be shorter or longer than the ammo acid sequence encoded by the exemplified nucleic acids shown in SEQ ID NO 2 and SEQ ID NO 9 Thus, in a preferred embodiment, included within the definition of BTRXή or NTR proteins are portions or fragments of the respective am o acid sequence encoded by the nucleic acid sequence provided herein In one embodiment herein, fragments of BTRXn or NTR proteins are considered BTRXή or NTR pioteins if a) a fragment shares at least one antigenic epitope with the corresponding exemplified sequence, b) has at least the indicated sequence homology, and c) preferably have an BTRXft or NTR biological activity or enzymatic activity as further defined herein In some cases, where the sequence is used diagnostically, that is, when the presence or absence of a BTRXΛ or an NTR protein nucleic acid is determined, only the indicated sequence identity is required The nucleic acids of the present invention may also be shorter or longer than the exemplified sequences in Figure 2 (SEQ ID NO 1) or Figure 5A (SEQ ID NO 10) The nucleic acid fragments include any portion of the nucleic acids provided herein which have a sequence not exactly previously identified, fragments having sequences with the indicated sequence identity to that portion not previously identified are provided in an embodiment herein In addition, as is more fully outlined below, a BTRXΛ or an NTR protein can be made that are longer than those depicted in Figure 1 (SEQ ID NO 2) and Figure 4 (SEQ ID NO 9), for example, by the addition of epitope or purification tags, the addition of other fusion sequences, or the elucidation of additional coding and non-coding sequences As descπbed below, the fusion of a NTR peptide to a fluorescent peptide, such as Green Fluorescent Peptide (GFP), is particularly preferred BTRX/j or NTR proteins may also be identified as encoded by BTRXt) or NTR nucleic acids which hybridize to the sequence depicted in the Figure 2 (SEQ ID NO 1) or Figure 5A (SEQ ID NO 10) or the complement thereof, as outlined herein Hybridization conditions are further described below In a preferred embodiment, when a BTRXf? or NTR protein is to be used to generate antibodies, a BTRX/7 or an NTR protein must share at least one epitope or determinant with the full length protein By "epitope" or "determinant" herein is meant a portion of a protein which will generate and/or bind an antibody Thus, in most instances, antibodies made to a smaller BTRX/7 or NTR protein will be able to bind to the full length protein In a preferred embodiment, the epitope is unique, that is, antibodies generated to a unique epitope show little or no cross-reactivity The term "antibody" includes antibody fragments, as are known in the art, including Fab, Fab 2 , single chain antibodies (Fv for example), chimeric antibodies, etc , either produced by the modification of whole antibodies or those synthesized de novo using recombinant DNA technologies (Harlow & Lane, 1988) In a preferred embodiment, an antibody to an BTRXή or NTR protein upon binding to an NTR protein reduce or eliminate at least one biological activity of the NTR protein as described herein That is, the addition of anti BTRXft or an anti-NTR protein antibodies (either polyclonal or preferably monoclonal) to anti-Btrxh or NTR proteins (or cells containing Brtxh or NTR proteins) may reduce or eliminate a BTRX/7 or an NTR activity Generally, for both proteins of the invention at least a 25% decrease in activity is preferred, with at least about 50% being particularly preferred and about a 95-100% decrease being especially preferred The antibodies of the invention specifically bind to either BTRXΛ or NTR proteins By "specifically bind" herein is meant that an antibody bind to a protein with a binding constant in the range of at least 10"*- 10 "6 M ' \ with a preferred range being 10 7 - 10 "9 M 1 Antibodies are further described below In the case of the BTRXft or NTR nucleic acid, the overall sequence identity of the nucleic acid sequence is commensurate with ammo acid sequence identity but takes into account the degeneracy in the genetic code and codon bias of different organisms Accordingly, the nucleic acid sequence identity may be either lower or higher than that of the encoded protein sequence Thus the NTR nucleic acid sequence identity of the nucleic acid sequence as compared to the nucleic acid sequence of the Figures is preferably greater than 75%, more preferably greater than about 80%, particularly greater than about 85% and most preferably greater than 90% in some embodiments the sequence identity will be as high as about 93 to 95 or 98% In a preferred embodiment, a NTR nucleic acid encodes a NTR protein, whereas a BTRXΛ nucleic acid encodes a BTRXt? protein As will be appreciated by those in the art, due to the degeneracy of the genetic code, an extremely large number of nucleic acids may be made, all of which encode either the BTRXΛ or the NTR proteins of the present invention Thus, having identified a particular ammo acid sequence, those skilled in the art could make any number of different nucleic acids, by simply modifying the sequence of one or more codons in a way which does not change the ammo acid sequence of the encoded protein In one embodiment, the BTRX/? or the NTR nucleic acid is determined through hybridization studies Thus, for example, nucleic acids which hybridize under high stringency to the nucleic acid sequence shown in Figure 2 (SEQ ID NO 1) or Figure 5A (SEQ ID NO 10), or their complement are considered either a BTRXfr or an NTR nucleic acid High stringency conditions are known in the art, see for example Sambrook ef al , Molecular Cloning A Laboratory Manual, 2d Edition, 1989, and Short Protocols in Molecular Biology, ed Ausubel, et al , and Tijssen, Techniques in Biochemistry and Molecular Biology-Hybridization with Nucleic Acid Probes, "Overview of principles of hybridization and the strategy of nucleic acid assays" (1993), all of which are hereby incorporated by reference in their entirety Stringent conditions are sequence-dependent and will be different in different circumstances Longer sequences specifically hybridize at higher temperatures Generally, stringent conditions are selected to be about 5-10°C lower than the thermal melting point (TJ for the specific sequence at a defined ionic strength pH The T m is the temperature (under defined ionic strength, pH, and nucleic acid concentration) at which 50% of the probes complementary to the target hybridize to the target sequence at equilibrium (as the target sequences are present in excess, at T m , 50% of the probes are occupied at equilibrium) Thus, it is known in the art that hybridization stringency is an objective measure of sequence rela.edness Stringent conditions will be those in which the salt concentration is less than about 1 0 M sodium ion, typically about 0 01 to 1 0 M sodium ion concentration (or other salts) at about pH 7 0 to 8 3 and the temperature is at least about 30 * C for short probes (e g about 10 to 50 nucleotides) and at least about 60'C for long probes (e g greater than about 50 nucleotides) Stringent conditions may also be achieved with the addition of destabilizing agents such as formamide In a preferred embodiment, high stringency conditions are 0 1X SSC at 65°C In another embodiment, less stringent hybridization conditions are used, for example, moderate or low stπngency conditions may be used, as are known in the art, see Maniatis and Ausubel, supra, and Tijssen, supra In a preferred embodiment, the BTRXft and NTR proteins and nucleic acids of the present invention are recombinant As used herein and further defined below, "nucleic acid" may refer to either DNA or RNA, or molecules which contain both deoxy- and πbonucleotides The nucleic acids include genomic DNA, cDNA and oligonucleotides including sense and anti-sense nucleic acids Such nucleic acids may also contain modifications in the πbose-phosphate backbone to increase stability and half life of such molecules in physiological environments The nucleic acid may be double stranded, single stranded, or contain portions of both double stranded or single stranded sequence As will be appreciated by those in the art, the depiction of a single strand ("Watson") also defines the sequence of the other strand ("Crick"), thus the sequences depicted in the Figures also include the complement of the sequence By the term "recombinant nucleic acid" herein is meant nucleic acid, originally formed in vitro, in general, by the manipulation of nucleic acid by an endonuclease and/or a polymerase and/or a ligase and/or a recombmase, in a form not normally found in nature Thus a recombinant BTRX/J or NTR nucleic acid, in a linear form, or an expression vector formed in vitro by ligatmg DNA molecules that are not normally joined, are both considered recombinant for the purposes of this invention It is understood that once a recombinant nucleic acid is made and remtroduced into a host cell or organism, it will replicate non-recombmantly, i e using the in vivo cellular machinery of the host cell rather than in vitro manipulations, however, such nucleic acids, once produced recombinantly, although subsequently replicated non- recombmantly, are still considered recombinant for the purposes of the invention Similarly, a "recombinant protein" is a protein made using recombinant techniques, i e through the expression of a recombinant nucleic acid as described herein A recombinant protein is distinguished from naturally occurring protein by at least one or more characteristics For example, the protein may be isolated or purified away from some or all of the proteins and compounds with which it is normally associated in its wild type host, and thus may be substantially pure For example, an isolated protein is unaccompanied by at least some of the material with which it is normally associated in its natural state, preferably constituting at least about 0 5%, more preferably at least about 5% by weight of the total protein in a given sample A substantially pure protein comprises at least about 75% by weight of the total protein, with at least about 80% being preferred, and at leasf about 90% being particularly preferred The definition includes the production of a BTRXΛ or NTR protein from one organism in a different organism or host cell Alternatively, the protein may be made at a significantly higher concentration than is normally seen, through the use of an inducible promoter or high expression promoter or by increasing the number of copies of a nucleic cid encoding the BTRXf? or NTR protein, such that the protein is made at increased concentration levels Alternatively, the protein may be in a form not normally found in nature, as in the addition of an epitope tag or ammo acid substitutions, insertions, and/or deletions, as discussed below In one embodiment, the present invention provides BTRX/7 and NTR protein variants These variants fall into one or more of three classes substitutional, insertional or deletional variants These variants ordinarily are prepared by site specific mutagenesis of nucleotides in the DNA encoding a BTRX/7 or an NTR protein, using cassette mutagenesis, alanine scanning mutagenesis, glycme scanning mutagenesis, PCR mutagenesis, gene shuffling or other techniques well known in the art, to produce a nucleic acid encoding the variant, and thereafter expressing the nucleic acid in recombinant host cell culture as outlined above However, variant BTRX/7 or NTR protein fragments having up to about 100- 150 residues may be prepared by in vitro synthesis using established techniques Ammo acid sequence variants are characterized by the predetermined nature of the variation, a feature that sets them apart from naturally occurring allelic or mterspecies variation of the BTRX/? or NTR protein am o acid sequence The variants typically exhibit the same qualitative biological activity as the naturally occurπng analogue, although variants can also be selected which have modified characteristics as will be more fully outlined below While the site or region for introducing an ammo acid sequence variation is predetermined, the mutation per se need not be predetermined For example, in order to optimize the performance of a mutation at a given site, random mutagenesis may be conducted at the target codon or region and the expressed BTRX/7 or NTR variants screened for the optimal combination of desired activity Techniques for making substitution mutations at predetermined sites in DNA having a known sequence are well known and include , for example, M13 primer mutagenesis, PCR mutagenesis, gene shuffling Screening of the mutants is done using assays of BTRX/7 or NTR protein activities and/or properties as defined herein Ammo acid substitutions are typically of single residues, insertions usually will be on the order of from about 1 to 20 am o acids, although considerably larger insertions may be tolerated Deletions range from about 1 to about 20 residues, although in some cases deletions may be much larger Substitutions, deletions, insertions or any combination thereof may be used to arrive at a final derivative Generally these changes are done on a few ammo acids to minimize the alteration of the molecule However, larger changes may be tolerated in certain circumstances When small alterations in the characteristics of the BTRXΛ or NTR protein are desired, substitutions are generally made in accordance with the following chart Chart I Original Residue Exemplary Substitutions Ala Ser Asp Glu Cys Ser Gin Asn Glu Asp Gly Pro His Asn, Gin lie Leu, Val Leu lie, Val Lys Arg, Gin, Glu Met Leu, He Phe Met, Leu, Tyr Ser Thr Thr Ser Trp Tyr Tyr Trp, Phe Val He, Leu Substantial changes in function or immunological identity are made by selecting substitutions that are less conservative than those shown in Chart I For example, substitutions may be made which more significantly affect the structure of the polypeptide backbone in the area of the alteration, for example the alpha-helical or beta-sheet structure, the charge or hydrophobicity of the molecule at the target site, or the bulk of the side chain The substitutions which in general are expected to produce the greatest changes in the polypeptide's properties are those in which (a) a hydrophilic residue, e g seryl or threonyl, is substituted for (or by) a hydrophobic residue, e g leucyl, isoleucyl, phenylalanyl, valyl or alanyl, (b) a cysteine or proline is substituted for (or by) any other residue, (c) a residue having an electropositive side chain, e g lysyl, argmyl, or histidyl, is substituted for (or by) an electronegative residue, e g glutamyl or aspartyl, or (d) a residue having a bulky side chain, e g phenylalanme, is substituted for (or by) one not having a side chain, e g glycine Covalent modifications of BTRX/7 or NTR polypeptides are included within the scope of this invention One type of covalent modification includes reacting targeted ammo acid residues of a BTRX/? or NTR polypeptide with an organic deπvatizing agent that is capable of reacting with selected side chains or the N-or C-terminal residues of a BTRX/7 or NTR polypeptide Deπvatization with bifunctional agents is useful, for instance, for crosslinkmg a BTRX/? or NTR protein to a water-insoluble support matrix or surface for use in the method of purifying anti-Btrxh or anti-NTR antibodies or screening assays, as is more fully described below Commonly used crosslinkmg agents include, e g , 1 ,1-bιs(dιazoacetyl)-2- phenylethane, glutaraldehyde, N-hydroxysuccinimide esters, for example, esters with 4-azιdosalιcylιc acid, homobifunctional imidoesters, including disuccinimidyi esters such as 3,3'-dιthιobιs(succιnιmιdyl- propionate), bifunctional maleimides such as bιs-N-maleιmιdo-1 ,8-octane and agents such as methyl- 3-[(p-azιdophenyl)dιthιo]propιoιmιdate Other modifications include deamidation of glutaminyl and asparaginyl residues to the corresponding glutamyl and aspartyl residues, respectively, hydroxylation of proline and lysine, phosphorylation of hydroxyl groups of seryl or threonyl residues, methylation of the "ammo groups of lysine, arginme, and histidine side chains [T E Creighton, Proteins Structure and Molecular Properties, W H Freeman & Co , San Francisco, pp 79-86 (1983)], acetylation of the N-terminal amme, and amidation of any C- termmal carboxyl group Another type of covalent modification of the BTRX/? or NTR polypeptide included within the scope of this invention comprises altering the native glycosylation pattern of the polypeptide "Altering the native glycosylation pattern" is intended for purposes herein to mean deleting one or more carbohydrate moieties found in native sequence of a BTRX/? or NTR polypeptide, if present, and/cr adding one or more glycosylation sites that are not present in the native sequence BTRX/? or NTR polypeptide Addition of glycosylation sites to Brtxh or NTR polypeptides may be accomplished by altering the ammo acid sequence thereof The alteration may be made, for example, by the addition of, or substitution by, one or more seπne or threonine residues to the native sequence BTRX/? or NTR polypeptide (for O-iinked glycosylation sites) The alteration also may be made, for example, by the addition of, or substitution by one or more Axn-Xaa-Ser/Thr sites (Xaa = any ammo acid) in the native sequence BTRX/7 or NTR polypeptide (for N-lmked glycosylation sites) The BTRX ? or NTR am o acid sequence may optionally be altered through changes at the DNA level, particularly by mutating the DNA encoding the BTRX/? or NTR polypeptide at preselected bases such that codons are generated that will translate into the desired ammo acids Another means of increasing the number of carbohydrate moieties on the BTRX ? or NTR polypeptide is by chemical or enzymatic coupling of glycosides to the polypeptide Such methods are described in the art, e g , in WO 87/05330 published 11 September 1987, and in Aplm and Wπston, CRC Cnt Rev Biochem , pp 259-306 (1981) Removal of carbohydrate moieties present on the BTRX/7 or NTR polypeptide may be accomplished chemically or enzymatically or by mutational substitution of codons encoding for ammo acid residues that serve as targets for glycosylation Chemical deglycosylation techniques are kno.vn in the art and described, for instance, by Hakimuddm, et al , Arch Biochem Biophvs , 259 52 (1987) and by Edge et al , Anal Biochem , 118 131 (1981) Enzymatic cleavage of carbohydrate moieties if present on polypeptides or variant polypeptides can be achieved by the use of a variety of endo-and exo- glycosidases as descπbed by Thotakura et al , Meth Enzymol , 138 350 (1987) Another type of covalent modification of BTRX/7 or NTR polypeptide comprises linking the BTRX/7 or NTR polypeptide to one of a variety of nonprotemaceous polymers, e g , polyethylene glycol, polypropylene glycol, or poiyoxyalkylenes, in the manner set forth in U S Patent Nos 4,640,835, 4,496,689, 4,301 ,144, 4,670,417, 4,791 ,192 or 4,179,337 BTRX/? or NTR polypeptides of the present invention may also be modified in a way to form chimeric molecules comprising an BTRX/? or NTR polypeptide fused to another, heterologous polypeptide or ammo acid sequence Encompassed within this embodiment are Btrxh-NTR fusions In one embodiment, such a chimeric molecule comprises a fusion of a BTRX/? or NTR polypeptide with a tag polypeptide which provides an epitope to which an anti-tag antibody can selectively bind The epitope tag is generally placed at the amino-or carboxyl-terminus of the BTRX/7 or NTR polypeptide but may be incorporated as an internal insertion or substitution The presence of such epitope-tagged forms of a BTRX/? or NTR polypeptide can be detected using an antibody against the tag polypeptide Also, provision of the epitope tag enables the BTRX/7 or NTR polypeptide to be readily purified by affinity purification using an anti-tag antibody or another type of affinity matrix that binds to the epitope tag In an alternative embodiment, the chimeric molecule may comprise a fusion of a BTRX/? or NTR polypeptide with an immunoglobulin or a particular region of an immunoglobulin For a bivalent form of the chimeric molecule, such a fusion could be to the Fc region of an IgG molecule as discussed further below Various tag polypeptides and their respective antibodies are well known in the art Examples include poly-histidme (poly-his) or poly-histidme-glycine (poly-his-gly) tags, the flu HA tag polypeptide and its antibody 12CA5 [Field et al , Mol Cell Biol , 8 2159-2165 (1988)], the c-myc tag and the 8F9, 3C7, 6E10, G4, B7 and 9E10 antibodies thereto [Evan et al , Molecular and Cellular Biology. 5 3610-3616 (1985)], and the Herpes Simplex virus glycoprotem D (gD) tag and its antibody [Paborsky et al , Protein Engineering, 3(6) 547-553 (1990)] Other tag polypeptides include the Flag-peptide [Hopp et al , BioTechnology, 6 1204-1210 (1988)], the KT3 epitope peptide [Martin et al , Science, 255 192-194 (1992)], tubulin epitope peptide [Skinner et al , J Biol Chem . 266 15163-15166 (1991)], and the T7 gene 10 protein peptide tag [Lutz-Freyermuth et al , Proc Natl Acad Sci USA. 87 6393-6397 (1990)] and the histidine tag and metal binding sites (Smith, Ann NY Acad Sci , 646 315-321 (1991)], with the Flag and histidine tag being preferred In an embodiment herein, nucleic acids comprising sequences homologous to the exemplified BTRX/7 and NTR proteins of other organisms or tissues or alleles are cloned and expressed as outlined below Thus, probe or degenerate polymerase chain reaction (PCR) primer sequences may be used to find other related BTRX/? or NTR proteins from humans or other organisms As will be appreciated by those in the art, particularly useful probe and/or PCR primer sequences include the unique areas of the BTRX/7 or NTR nucleic acid sequence As is generally known in the art, preferred PCR primers are from about 15 to about 35 nucleotides in length, with from about 20 to about 30 being preferred, and may contain inosme as needed The conditions for the PCR reaction are well known in the art (Innis ef al , 1990) It is therefore also understood that provided along with the sequences in the sequences listed herein are portions of those sequences, wherein unique portions of 15 nucleotides or more are particularly preferred The skilled artisan can routinely synthesize or cut a nucleotide sequence to the desired length Once isolated from its natural source, e g , contained within a plasmid or other vector or excised therefrom as a linear nucleic acid segment, the recombinant Brtxh or NTR nucleic acid can be further- used as a probe to identify and isolate related Brtxh or NTR nucleic acids It can also be used as a "precursor" nucleic acid to make modified or variant BTRX/7 or NTR nucleic acids and proteins Using the nucleic acids of the present invention which encode an BTRX ? or NTR protein, a variety of expression vectors are made The expression vectors may be either self-replicating extrachromosomal vectors or vectors which integrate into a host genome Generally, these expression vectors include transcriptional and translational regulatory nucleic acid operably linked to the nucleic acid encoding the BTRX/? or NTR protein The term "control sequences" refers to nucleic acid sequences necessary for the expression of an operably linked coding sequence in a particular host organism The control sequences that are suitable for prokaryotes, for example, include a promoter, optionally an operator sequence, and a πbosome binding site Eukaryotic cells are known to utilize promoters, polyadenylation signals, and enhancers Nucleic acid is "operably linked" when it is placed into a functional relationship with another nucleic acid sequence For example, DNA for a presequence or secretory leader is operably linked to DNA for a polypeptide if it is expressed as a preprotem that participates in the secretion of the polypeptide, a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the sequence, or a πbosome binding site is operably linked to a coding sequence if it is positioned so as to facilitate translation As another example, operably linked refers to DNA sequences linked so as to be contiguous, and, in the case of a secretory leader, contiguous and in reading phase However, enhancers do not have to be contiguous Linking is accomplished by ligation at convenient restriction sites If such sites do not exist, the synthetic oligonucleotide adaptors or linkers are used in accordance with conventional practice The transcriptional and translational regulatory nucleic acid will generally be appropriate to the host cell used to express the 3TRX ? or NTR protein, for example, transcriptional and translational regulatory nucleic acid sequences from barley are preferably used to express the NTR protein in barley Numerous types of appropriate expression vectors, and suitable regulatory sequences are known in the art for a variety of host cells In general, the transcriptional and translational regulatory sequences may include, but are not limited to, promoter sequences, ribosomal binding sites, transcriptional start and stop sequences, translational start and stop sequences, and enhancer or activator sequences In a preferred embodiment, the regulatory sequences include a promoter and transcriptional start and stop sequences Promoter sequences encode either constitutive or inducible promoters The promoters may be either naturally occurring promoters or hybrid promoters Hybrid promoters, which combine elements of more than one promoter, are also known in the art, and are useful in the present invention In addition, the expression vector may comprise additional elements For example, the expression vector may have two replication systems, thus allowing it to be maintained in two organisms, for example in mammalian or plant cells for expression and in a procaryotic host for clorwng and amplification Furthermore, for integrating expression vectors, the expression vector contains at least one sequence homologous to the host cell genome, and preferably two homologous sequences which flank the expression construct The integrating vector may be directed to a specific locus in the host cell by selecting the appropriate homologous sequence for inclusion in the vector Constructs for integrating vectors are well known in the art In addition, in a preferred embodiment, the expression vector contains a selectable marker gene to allow the selection of transformed host cells Selection genes are well known in the art and will vary A preferred expression vector system for use in plant cells and for production of transgenic plants are provided herein and in the Examples BTRX 7 or NTR proteins of the present invention are produced by cultuπng a host cell transformed with an expression vector containing nucleic acid encoding a BTRX 7 or NTR protein, under the appropriate conditions to induce or cause expression of the BTRX/? or NTR protein The conditions appropriate for BTRX/? or NTR protein expression will vary with the choice of the expression vector and the host cell, and will be easily ascertained by one skilled in the art through routine experimentation For example, the use of constitutive promoters in the expression vector will require optimizing the growth and proliferation of the host cell, while the use of an inducible promoter requires the appropriate growth conditions for induction In addition, in some embodiments, the timing of the harve&t-is important For example, the baculoviral systems used in insect cell expression are lytic viruses, and thus harvest time selection can be crucial for product yield Appropriate host cells include plant, yeast, bacteria, archebacteπa, fungi, insect, and animal cells, including mammalian cells Of particular interest are plant embryos, plant seeds and grains, root cells stem cells, leaf cells, and other plant cells, Drosophila melangaster cells, Saccharomyces cerevisiae and other yeasts, £ coli, Bacillus subtilis, SF9 cells, C129 cells, 293 cells, Neurospora, BHK, CHO, COS, and HeLa cells, fibroblasts, Schwanoma cell lines, immortalized mammalian myeloid and lymphoid cell lines, with HeLa, SF9, and plant cells being preferred In a preferred embodiment, the BTRX/7 or NTR proteins are expressed in seed, gram, root, stem, leaf cells etc of dicotyledonous plants and monocotyledonous plants Thus, BTRX ? and NTR are expressed, for example, in wheat {Tπticum spp ), rice {Oryza spp ), barley (Hordeum spp ), oat {Avena spp ), rye (Seca/e spp ), maize, corn (Zea mays), sorghum {Sorghum spp ), millet (Pennisetum spp ), Brassica spp , soybean, cotton, beans in general, rape/canola, alfalfa, flax, sunflower, safflower, cotton, tobacco, flax, peanut, clover, cowpea, grapes, forages grass varieties, vegetables such as lettuce, tomato, curcurbits, cassava, potato, carrot, radish, pea, lentils, cabbage, sugar beets, cauliflower, broccoli, sugar beats, Brussels sprouts, peppers, tree fruits such as citrus, apples, pears, peaches, apricots, walnuts, and ornamentals such as turf grasses, carnations and roses In a preferred embodiment, the present invention can be employed with barley genotypes including, but not limited to Morex, Harrington , Crystal, Stander, Moravian III, Galena, Salome, Steptoe, Klages, Baronesse, and with wheat genotypes including, but not limited to Yecora Rojo, Bobwhite, Karl and Anza In general, the invention is particularly useful in cereals A number of recombinant vectors suitable for stable transfection or transformation of plant cells or for the establishment of transgenic plants have been described including those descπbed in Weissbach and Weissbach (1989), and Gelvm et al (1990) Typically, plant transformation vectors include one or more cloned plant genes (or cDNAs) under the transcriptional control of 5' and 3' regulatory sequences, and a dominant selectable marker Such plant transformation vectors typically also contain a promoter regulatory region (e g , a regulatory region controlling inducible or constitutive, environmentally or developmentally regulated, or cell- or tissue-specific expression), a transcription initiation start site, a πbosome binding site, an RNA processing signal, a transcription termination site, and/or a polyadenylation signal Examples of constitutive plant promoters that may be useful for expressing the an operatively linked nucleic acid include the cauliflower mosaic virus (CaMV) 35S promoter, which confers constitutive, high-level expression in most plant tissues (see, e g, Odel ef al , 1985, Dekeyser ef al , 1990, Terada and Shimamoto, 1990, Benfey and Chua, 1990), the nopaline synthase promoter (An ef al , 1988), the maize ubiquitm promoter (Chπstianson & Quail, 1996) and the octopme synthase promoter (Fromm ef al , 1989) A variety of plant gene promoters that are regulated in response to environmental, hormonal, chemical, and/or developmental signals, also can be used for expression of the Btrwh or NTR nucleic acid in plant cells, including promoters regulated by (a) heat (Callis ef al , 1988, Amley, ef al 1993, Gilmartin ef al 1992), (b) light (e g, the pea rbcS-3A promoter, Kuhlemeier ef al , 1989, and the maize rbcS promoter, Schaffner and Sheen, 1 99 1 ), (c) wounding (e g, wunl, Siebertz ef al , 1 9893, (d) hormones, such as abscisic acid (Marcotte ef al , 1989), and (e) chemicals such as methyl jasmmate or salicylic acid (see also Gatz, 1997) In an alternative embodiment, tissue or organ specific (root, leaf, flower, and seed for example) promoters (Carpenter ef al , 1992, Denis ef al , 1993, Opperman ef al , 1994, Stockhauser ef al , 1997, Roshal et al , 1987, Schernthaner ef al , 1988, Bustos ef al , 1989) can be operably linked to the coding sequence to obtain particular expression in respective organs For instance, monocot tissue-specific promoters may be used to attain expression in the aleurone (U S Patent No 5,525,716) or the endosperm (U S Patent No 5,677,474) of cereal and other grains In a preferred embodiment, a transgene of the invention, the Btrwh or NTR nucleic acid, is expressed in an edible part of a plant By "edible" herein is meant at least a part of a plant that is suitable for consumption by humans or animals (fish, crustaceans, isopods, decapods, monkeys, cows, goats, pigs, rabbits, horses, birds (chickens, parrots etc) Accordingly, "edible" embraces food for human consumption and feed for animal consumption and includes, for example, dough, bread, cookies, pasta, pastry, beverages, beer, food additives thickeners, malt, extracts made from an edible part of plants, animals feeds, and the like An edible part of a plant includes for example, a root, a tuber, a seed, gram, a flower, fruit, leaf etc The skilled artisan is aware that expression of the transgene is effected in any tissue, organ or part of a plant by employing a promoter that is active in the selected part of the plant the transgene is to be expressed In a preferred embodiment the transgene is expressed in a seed or gram, preferably under control of a seed- or grain-specific promoter The expression of a Btrwh or NTR nucleic acid transgene in seeds or grains according to the present invention is preferably accomplished by operably linking a seed-specific or gram-specific promoter to the nucleic acid molecule encoding the transgene Btrwh or NTR protein In this context, "seed-specific" indicates that the promoter has enhanced activity in seeds compared to other plant tissues, it does not require that the promoter is solely active in the seeds Accordingly, "grain-specific" indicates that the promoter has enhanced activity in grains compared to other plant tissues, it does not require that the promoter is solely active in the gram Preferably, the seed- or gram-specific promoter selected will, at the time when the promoter is most active in seeds, produce expression of a protein in the seed of a plant that is at least about two-fold greater than expression of the protein produced by that same promoter in the leaves or roots of the plant However, given the nature of the Btrwx and NTR protein, it may be advantageous to select a seed- or gram-specific promoter that causes little or no protein expression in tissues other than seed or gram In a preferred embodiment, a promoter is specific for seed and grain expression, such that, expression in the seed and gram is enhanced as compared to other plant tissues but does not require that the promoter be sole activity in the gram or seed In a preferred embodiment, the promoter is "specific" for a structure or element of a seed or gram, such as an embryo-specific promoter In accordance with the definitions provided above, an embryo-specific promoter has enhanced activity in an embryo as compared to other parts of a seed or gram or a plant and does not require its activity to be limited to an embryo In a preferred embodiment, the promoter is "maturation-specific" and accordingly has enhanced activity developmentally during the maturation of a part of a plant as compared to other parts of a plant and does not require its activity to be limited to the development of one part of a plant A seed- or grain-specific promoter may produce expression in various parts of the seed or gram, including the endosperm, embryo, aleurone etc or gram Any seed- or gram-specific promoter may be used for this purpose, although ι* will be advantageous to select a seed- or gram-specific promoter that produces high level expression of the protein in the plant seed or grain Known seed- or gram-specific promoters include those associated with genes that encode plant seed storage proteins such as genes encoding barley hordeins, rice glutelms, oryzins, or prolamines, wheat gliadms or gluten s, maize zems or glutelms, maize embryo-specific promoter, oat glutelms, sorghum kafiπns, millet pennisetms, or rye secalms The barley hordein promoters (described in more detail below) are seed- or gram-specific promoters that were used in the illustrative Examples In certain embodiments, the seed- or gram-specific promoter that is selected is a maturation-specific promoter The use of promoters that confer enhanced expression during seed or grain maturation (such as the barley hordein promoters) may result in even higher levels of thioredoxin expression in the seed By "seed or grain-maturation" herein refers to the period starting with fertilization in which metabolizable food reserves (e g , proteins, lipids, starch, etc ) are deposited in the developing seed, particulariy in storage organs of the seed, including the endosperm, testa, aleurone layer, embryo, and scutellar epithelium, resulting in enlargement and filling of the seed and ending with seed desiccation Members of the grass family, which include the cereal grains, produce dry, one-seeded fruits This type of fruit, is strictly speaking, a caryopsis but is commonly called a kernel or gram The caryopsis of a fruit coat or pericarp, which surrounds the seed and adhere tightly to a seed coat The seed consists of an embryo or germ and an endosperm enclosed by a nucellar epidermis and a seed coat Accordingly the grain comprises the seed and its coat or pericarp The seed comprises the embryo and the endosperm (R Carl Hoseney in "Principles of Cereal Science and Technology", expressly incorporated by reference in its entirety) In a preferred embodiment a hordein promoter is operably linked to a BTRX/? or NTR nucleic acid By "hordein promoter" and grammatical equivalents herein is meant, a barley promoter that directs transcπption of a hordein gene in bariey seeds or gram A number of barley hordein genes and associated promoters have been described and characteπzed, including those for the B-, C-, D-, and Gamma-hordeins (Brandt et al , 1985, Forde ef al , 1985, Rasmussen and Brandt, 1986, Sørensen ef al , 1996) The activities of these promoters in transient expression assays have also been characterized (Entwistle ef al , 1991 , Muller and Knudesen, 1993, Sørensen et al, 1996) While any hordein promoter may be employed for this invention, the specific Examples provided describe the use of the promoter sequences from the B,- and D-hordein genes of barley The nucleic acid sequences of the barley B,- and D-hordein genes are shown in SEQ ID NOs 11 and 12 , respectively and in Figures 11 and 12 (the promoter region excludes those nucleotides that encode the hordein signal peptide that is shown underlined) Sørensen ef al , (1996) describes plasmids that comprise the B-- and D-hordein promoters operably linked to a beta-glucuronidase gene {uidA, gus) and the Agrobactenum tumefaciens nopaline synthase 3' poiyadenylation site (nos) These plasmids may be conveniently utilized as sources of both the hordein promoters and the nos poiyadenylation site One of skill in the art will appreciate that the length of the hordein promoter region may also be greater or less than the sequences depicted in Figures 11 and 12 For example, additional 5' sequence from the hordein gene upstream region may be added to the promoter sequence, or bases may be removed from the depicted sequences However, any hordein promoter sequence must be able to direct transcription of an operably linked sequence in plant seed or grain The ability of a barley hordein promoter to direct transcription of a protein in a plant seed may readily be assessed by operably linking the promoter sequence to an open reading frame (ORF) that encodes a readily detectable protein, such as the gus ORF, introducing the resulting construct into plants and then assessing expression of the protein in seeds of the plant (see Sørensen et al , 1996) A hordein promoter will typically confer seed-specific expression, meaning that expression of the protein encoded by the operably linked ORF will generally be at least about twice as high (assessed on an activity basis) in seeds of the stably transfected plant compared to other tissues such as leaves More usually, the hordein promoter will produce expression in seeds that is at least about 5 times higher than expression in other tissues of the plant Functionεl homologs of the barley hordein promoters disclosed herein may be obtained from other plant species, such as from other monocots, including wheat, rice and corn Such homologs may have specified levels of sequence identity with the prototype hordein promoters (e g , at least 40% sequence identity) The functional homologs retain hordein promoter function, i e , retain the ability to confer seed- or gram-specific expression of operably linked ORFs when introduced into plants (Mams ef a/ , 1988, Mena ef al , 1998) Accordingly, where reference is made herein to a hordein promoter, it will be understood that such reference includes not only nucleic acid molecules having the sequences of the prototypical sequences disclosed herein (or variations on these sequences), but also promoters from hordein gene homologs Also included within the scope of such terms are molecules that differ from the disclosed prototypical molecules by minor variations Such variant sequences may be produced by manipulating the nucleotide sequence of hordein promoter using standard procedures such as site-directed mutagenesis or the polymerase chain reaction Preferably, the seed- or gram- specificity of the promoter is retained Examples of dicot promoters that can be used include for example soybean glycinms and con-glycinms, and kidney bean phaseo n promoters In a preferred embodiment, the vector for plant expression of BTRX/? and NTR polypeptides comprises a signal sequence which encodes a signal peptide As described in the Examples below, the inventors have discovered that the level of expression of a transgene in seed or gram can be enhanced by the presence of a signal peptide In one of the Examples described below, the B, hordein signal peptide was utilized In particular, it was discovered that the expression of thioredoxin protein in seed or gram is enhanced when the ORF encoding the protein is operably linked to both a hordein promoter and a hordein signal sequence encoding the signal peptide (For convenience, the nucleic acid sequence encoding a signal peptide is referred to herein as a signal sequence (SS) ) While not wishing to be bound by theory, it is proposed that the hordein signal peptide directs expression of the thioredoxin protein to a protected subcellular location, such as a vacuole or protein body It is further proposed that proteins directed to such vacuoles are protected from proteolysis during certain stages of seed or gram maturation In addition, the sequestration of the BTRX/? or NTR protein to such a location may also serve to protect the maturing seeds or grain from detrimental effects associated with over-expression of said proteins The hordein signal peptide typically comprises about the first 15-25 am o acids of the hordein gene ORF, more usually about 18-21 am o acids The nucleotide and ammo acid sequences of the hordein signal sequence and peptide of the prototypical barley B1- and D-hordein genes are shown in SEQ ID NO 11-12 and Figures 11 and 12 One of skill in the art will appreciate that while the B hordem signal sequence and signal peptide are utilized in the examples described below, the invention is not limited to these specific sequences For example, homologous sequences may be used as effectively, as may sequences that differ in exact nucleotide or ammo acid sequences, provided that such sequences result in enhanced levels of the encoded protein in immature seed or grain Typically, "enhanced expression" will be expression that is about twice that observed with an equivalent construct lacking the signal sequence Accordingly, the term "hordein signal sequence" and "horαein signal peptide" includes not only the particular sequences shown herein, but also homologs and variants of these sequences Furthermore, the invention is not limited to the use of hordein signal peptides Other signal peptides that serve to localize the thioredoxin co-translationally or post-translationally to a selected seed, gram or cell compartment may be employed Other such signal sequences include those associated with storage proteins in maize, rice, wheat, soybeans, beans, and tobacco (see for example Bagga ef al , 1997, Torrent ef a/ , 1997, Wu et al , 1998, Zheng et al , 1995, Gnmwade et al , 1996, Conrad et al , 1998, and Takaiwa ef al , 1995 ) In a preferred embodiment, plant transformation vectors may also include RNA processing signals, for example introns, which may be positioned upstream or downstream of the ORF sequence in the transgene In addition, the expression vectors may also include additional regulatory sequences from the 3' untranslated region of plant genes, e g , a 3' terminator region to increase stability of the mRNA, such as the Pl-ll terminator region of potato or the octopme or nopaline synthase (nos) 3' terminator regions Finally, as noted above, plant transformation vectors may also include dominant selectable marker genes to allow for the ready selection of transformants Such genes include those encoding antibiotic resistance genes (e g, resistance to hygromycin, kanamycm, bleomycm, G418, streptomycin or spectinomycin) and herbicide resistance genes (e g , phosphinothπcin acetyltransferase) The vector and transcriptional regulatory elements used for transgene expression is selected at the discretion of the practitioner In some instances, enhanced BTRX/? or NTR polypeptide expression and/or activity is desired, and the respective transgene encoding sequence is operably linked to a high-level promoter such as the maize ubiquit 1 promoter Enhanced BTRX/? or NTR activity may also be achieved by introducing into a plant a transformation vector containing a variant form of the BTRX/? or NTR polypeptide encoding sequence, for example a form which vanes from an exemplified sequence but encodes a protein that retains BTRX ? or NTR biological activity Over-expression of BTRX ? or NTR in plant or other type of eukaryotic or procaryotic expression system is usually measured as the increase in the BTRX/? or NTR activity present in a sample Such over-expression can be measured using standard thioredoxin activity and NTR activity assays As used here, cells, tissues, or plants over-expressing BTRX/? or NTR, or homologous or derived proteins having BTRX/? or NTR polypeptide activity, generally will have activity levels attributable of at least 5% over that found in the equivalent wild-type (nontransformed) sample Where particularly high levels of over-expression are desired, transformed cells will express at least 30%, more preferably at least 50%, even more preferred at least 70%, or most preferred at least 100% more thioredoxin or NTR activity attributable in comparison to an equivalent wild-type or null segregant sample Overexpression of BTRX/? or NTR polypeptide activity also may be measured by assessing the amount of protein in plant tissues using well-known procedures In an alternative embodiment, a reduction of BTRX/? or NTR activity, preferably in a transgenic plant, may be obtained by introducing into plants an antisense construct based on a BTRX/? or NTR encoding sequence For antisense suppression, a BTRX/? or NTR encoding sequence is arranged in reverse orientation relative to the promoter sequence in the transformation expression vector The introduced sequence need not be a full length barley thioredoxin h or NTR encoding sequence, and need not be exactly homologous to the native thioredoxin h or NTR cDNA or gene found in the plant species, type, cultivar, varietal, or subspecies to be transformed Generally, however, where the introduced sequence is of shorter length, a higher degree of homology to the native thioredoxin sequence will be needed for effective antisense suppression The introduced antisense sequence in the vector generally will be at least 30 nucleotides in length, and improved antisense suppression will typically be observed as the length of the antisense sequence increases Preferably, the length of the antisense sequence in the vector will be greater than 100 nucleotides Transcription of an antisense construct as described results in the production of RNA molecules that are the reverse complement of mRNA molecules transcribed from the endogenous thioredoxin or NTR gene in the plant cell Although the exact mechanism by which antisense RNA molecules interfere with gene expression has not been elucidated, without being bound by theory, the antisense RNA molecules bind to the endogenous mRNA molecules and thereby inhibit translation of the endogenous mRNA The production and use of anti-sense constructs are disclosed, for instance, in U S Pat Nos 5,773,692 (using constructs encoding anti-sense RNA for chlorophyll a/b binding protein to reduce plant chlorophyll content), and 5,741,684 (regulating the fertility of pollen in various plants through the use of anti-sense RNA to genes involved in pollen development or function) Suppression of endogenous thioredoxin or NTR gene expression can also be achieved using ribozymes Ribozymes are synthetic RNA molecules that possess highly specific endoπbonuclease activity The production and use of ribozymes are disclosed in U S Patent No 4,987,071 to Cech and U S Patent No S, 543,508 to Haselhoff Inclusion of ribozyme sequences within antisense RNAs may be used to confer RNA cleaving activity on the antisense RNA, such that endogenous mRNA molecules that bind to the antisense RNA are cleaved leading to an enhanced antisense inhibition of endogenous gene expression In another embodiment, constructs from which a BTRX/? or NTR encoding sequence (or a variant thereof) is overexpressed may be used to obtain co-suppression of the endogenous thioredoxin gene in the manner described in U S Patent No 5,231 ,021 to Jorgensen Such co-surpressιon (also termed sense suppression) does not require that the entire BTRX/? or NTR encoding sequence be introduced into the plant cells, nor does it require that the introduced sequence be exactly identical to the endogenous thioredoxin gene However, as with antisense suppression, the suppressive efficiency is enhanced as (1) the introduced sequence is lengthened and (2) the sequence similarity between the introduced sequence and the endogenous thioredoxin h gene is increased In another embodiment, constructs expressing an untranslatable form of a BTRX/? or NTR message may also be used to suppress the expression of endogenous thioredoxin or NTR activity Methods for producing such constructs are described in U S Patent No 5,583,021 to Dougherty Preferably, such constructs are made by introducing a premature stop codon into the BTRX/? or NTR ORF Methods of introducing exogenous nucleic acids into a plant host or plant host cells are known in the art Accordingly, the transformation vector is introduced into plant cells by one of a number of techniques (e g, electroporation) and progeny plants containing the introduced nucleic acid molecule are selected Preferably all or part of the transformation vector will stably integrate into the genome of the plant cell The part of the transformation vector that integrates into the plant cell, and which contains the introduced encoding sequence and associated expression contrβHinq sequences (the introduced "transgene"), may be referred to as the recombinant expression cassette Selection of progeny plants containing the introduced transgene may be made based upon the detection of an altered phenotype Such a phenotype may result directly from the expressed encoding sequence cloned into the transformation vector (for instance, altered thioredoxin h expression) or may be manifested as enhanced resistance to a chemical agent (such as an antibiotic) as a result of the inclusion of a dominant selectable marker gene incorporated into the transformation vector Successful examples of the modification of plant characteristics by transformation with cloned cDNA sequences are replete in the technical and scientific literature Selected examples, which serve to illustrate the knowledge in this field of technology include U S Pat No 5,571 ,706 ("Plant Virus Resistance Gene and Methods") U S Pat No 5,677,175 ("Plant Pathogen Induced Proteins") U S Pat No 5,750,386 ("Pathogen-Resistant Transgenic Plants") U S Pat No 5,597,945 ("Plants Genetically Enhanced for Disease Resistance") U S Pat No 5,589,615 ("Process for the Production of Transgenic Plants with Increased Nutritional Value Via the Expression of Modified 2S Storage Albumins") U S Pat No 5 750,871 ("Transformation and Foreign Gene Expression in Brassica Species") U S P No 5,268,526 ("Over-expression of Phytochrome in Transgenic Plants") U S Pat No 5,780,708 ("Fertile Transgenic Corn Plants") U S Pat No 5,538,880 ("Method For Preparing Fertile Transgenic Corn Plants') U S Pat No 5,773,269 ("Fertile Transgenic Oat Plants") U S Pat No 5,736,369 ("Method For Producing Transgenic Cereal Plants") U.S Pat No 5,610,042 ("Methods For Stable Transformation of Wheat") U S Pat No 5,780,709 ("Transgenic Maize with Increased Mannitol Content") PCT publication WO 98/48613 ("Compositions and Methods for Plant Transformation and Regeneration") These examples include descriptions of transformation vector selection, transformation techniques and the construction of vectors designed to express, over-express, or under-express the introduced nucleic acid molecule In light of the foregoing and the provision herein of the BTRX/? or NTR encoding sequence, it is thus apparent that one of skill in the art will be able to introduce these nucleic acid sequences, or homologous or derivative forms of this molecule, into plant cells in order to produce plants having altered or enhanced barley thioredoxin activity Transformation and regeneration of both monocotyledonous and dicotyledonous plant cells is routine in the art and the practitioner will determine the appropriate transformation technique The choice of method will vary with the type of plant to be transformed, those skilled in the art will recognize the suitability of particular methods for given plant types Suitable methods may ικclude, but are not limited to electroporation of plant protoplasts, liposome-mediated transformation, polyethylene glycol (PEG) mediated transformation, transformation using viruses, micro-injection of plant cells, micro-projectile bombardment of plant cells, vacuum infiltration, and Agrobactenum tumefaciens (AT)-medιated transformation Typical procedures for transforming and regenerating plants are described in the patent documents listed at the beginning of this section In addition, certain developments particularly enhance regeneration techniques for monocot plants (see, for instance, U S Patents No 4,666,844 and 5,589,617, and PCT application WO 98/48613) For instance, a vector comprising a barley thioredoxin /?-encodιng nucleic acid can be stably introduced to barley plants as described in a number of published protocols, including Wan and Lemaux 1994, Lemaux ef al , 1996, and Cho ef al , 1998a-c) Depending on the transformation and regeneration protocol followed, transformed plants may be selected using a dominant selectable marker incorporated into the transformation vector or carried on a companion vector used for co-transformation Typically, such a marker will confer antibiotic or herbicide resistance on the seedlings of transformed plants, and selection of transformants can be accomplished by exposing the seedlings to appropriate concentrations of the antibiotic After transformed plants are selected and grown to maturity, they can be assayed using the methods descπbed herein to determine whether expression of thioredoxin h has been altered as a result of the introduced transgene Expression of the transformed barley thioredoxin h protein can be determined by Western blot analysis of transformed plant tissues or extracts using standard procedures BTRX/? and NTR activity assays, as discussed above, can be used to determine the activity of the expressed transgenic Btrwx or NTR Untransformed and negative segregant plants also are preferably assayed for activity so the background level of BTRX/7 or NTR activity (provided by expression of endogenous genes, when present and being expressed) can be determined In a preferred embodiment, the BTRX/? or NTR proteins are expressed in mammalian cells Mammalian expression systems are also known in the art, and include retroviral systems A mammalian promoter is any DNA sequence capable of binding mammalian RNA polymerase and initiating the downstream (3') transcription of a coding sequence for BTRX/? or NTR protein into mRNA A promoter will have a transcription initiating region, which is usually placed proximal to the 5' end of the coding sequence, and a TATA box, usually located about 25-30 base pairs upstream of the transcription initiation site The TATA box is thought to direct RNA polymerase II to begin RNA synthesis at the correct site A mammalian promoter will also contain an upstream promoter element (enhancer element), typically located within 100 to 200 base pairs upstream of the TATA box An upstream promoter element determines the rate at which transcπption is initiated and can act in either oπentation Of particular use as mammalian promoters are the promoters from mammalian viral genes, since the viral genes are often highly expressed and have a broad host range Examples include the SV40 early promoter, mouse mammary tumor virus LTR promoter, adenovirus major late promoter, herpes simplex virus promoter, and the CMV promoter Typically, transcription termination and poiyadenylation sequences recognized by mammalian cells are regulatory regions located 3' to the translation stop codon and thus, together with the promoter elements, flank the coding sequence The 3' terminus of the mature mRNA is formed by site-specific post-translational cleavage and poiyadenylation Examples of transcription terminator and poiyadenylation signals include those derived form SV40 The methods of introducing exogenous nucleic acid into mammalian hosts, as well as other hosts, is well known in the art, and will vary with the host cell used Techniques include dextran-mediated transfection, calcium phosphate precipitation, polybrene mediated transfection, protoplast fusion, electroporation, viral infection, encapsulation of the polynucleotιde(s) in liposomes, and direct microinjection of the DNA into nuclei In a preferred embodiment, BTRX/? or NTR proteins are expressed in bacterial systems Bacterial expression systems are well known in the art A suitable bacterial promoter is any nucleic acid sequence capable of binding bacterial RNA polymerase and initiating the downstream (3') transcription of the coding sequence of BTRX/? or NTR protein into mRNA A bacterial promoter has T transcription initiation legion which is usually placed proximal to the 5' end of the coding sequence This transcription initiation region typically includes an RNA polymerase binding site and a transcπption initiation site Sequences encoding metabolic pathway enzymes provide particularly useful promoter sequences Examples include promoter sequences derived from sugar metabolizing enzymes, such as galactose, lactose and maltose, and sequences derived from biosynthetic enzymes such as tryptophan Promoters from bacteπophage may also be used and are known in the art In addition, synthetic promoters and hybrid promoters are also useful, for example, the tac promoter is a hybrid of the trp and lac promoter sequences Furthermore, a bacterial promoter can include naturally occurπng promoters of non-bacterial origin that have the ability to bind bacterial RNA polymerase and initiate transcription In addition to a functioning promoter sequence, an efficient πbosome binding site is desirable In £ coli, the πbosome binding site is called the Shme-Delgarno (SD) sequence and includes an initiation codon and a sequence about 3-9 nucleotides in length located about 3-11 nucleotides upstream of the initiation codon The expression vector may also include a signal peptide sequence that provides for secretion of the BTRX/? or NTR protein in bacteria The signal sequence typically enccdes a signal peptide comprised of hydrophobic ammo acids which direct the secretion of the protein from the cell, as is well known in the art The protein is either secreted into the growth media (gram-positive bacteria) or into the peπplasmic space, located between the inner and outer membrane of the cell (gram-negative bacteria) The bacteπal expression vector may also include a selectable marker gene to allow for the selection of bacterial strains that have been transformed Suitable selection genes include genes which render the bacteria resistant to drugs such as ampicillin, chloramphenicol, erythromycin, kanamycm, neomycin and tetracyclme Selectable markers also include biosynthetic genes, such as those in the histidine, tryptophan and leucine biosynthetic pathways These components are assembled into expression vectors Expression vectors for bacteria are well known in the art, and include vectors for Bacillus subtilis, £ coli, Streptococcus cremons, and Streptococcus lividans, among others The bacterial expression vectors are transformed into bacterial host cells using techniques well known in the art, such as calcium chloride treatment, electroporation, and others In one embodiment, BTRX/7 or NTR proteins are produced in insect cells Expression vectors for the transformation of insect cells, and in particular, baculovirus-based expression vectors, are well known in the art In a preferred embodiment, BTRX/? or NTR protein is produced in yeast cells Yeast expression systems are well known in the art, and include expression vectors for Saccharomyces cerevisiae, Candida albicans and C maltosa, Hansenula polymorpha, Kluyveromyces fragihs and K lactis, Pichia guilleπmondii and P pastoπs, Schizosaccharomyces pombe, and Yarrowia lipolytica Preferred promoter sequences for expression in yeast include the inducible GAL1J0 promoter, the promoters from alcohol dehydrogenase, enolase, glucokmase, glucose-6-phosphate isomerase, glyceraldehyde- 3-phosphate-dehydrogenase, hexokmase, phosphofructokmase, 3-phosphogly cerate mutase, pyruvate kinase, and acid phosphatase genes Yeast selectable markers include ADE2, HIS4, LEU2, TRP1 , and ALG7, which confers resistance to tunicamycin, the neomycm phosphotransferase gene, which confers resistance to G418, and the CUP1 gene, which allows yeast to grow in the presence of copper ions The BTRX/? or NTR protein may also be made as a fusion protein, using techniques well known in the art Thus, for example, for the creation of monoclonal antibodies, if the desired epitope is small, the BTRX/7 or NTR protein may be fused to a carrier protein to form an immunogen Alternatively, the BTRX ? or NTR may be made as a fusion protein to increase expression, or for other reasons For example, when the BTRX/7 or NTR protein is an H vulgare BTRX/7 or NTR peptide, the nucleic acid encoding the peptide may be linked to another nucleic acid for expression purposes Similarly, BTRX/? or NTR proteins of the invention can be linked to protein labels, such as green fluorescent protein (GFP), red fluorescent protein (RFP), blue fluorescent protein (BFP), yellow fluorescent protein (YFP), etc In one embodiment, the BTRX/7 or NTR nucleic acids, proteins and antibodies of the invention are labeled By "labeled" herein is meant that a compound has at least one element, isotope or chemical compound attached to enable the detection of the compound In general, labels fall into three classes a) isotopic labels, which may be radioactive or heavy isotopes, b) immune labels, which may be antibodies or antigens, and c) colored or fluorescent dyes The labels may be incorporated into the compound at any position In a preferred embodiment, the BTRX/? or NTR protein is purified or isolated after expression BTRX/? or NTR proteins may be isolated or purified in a variety of ways known to those skilled in the art depending on what other components are present in the sample Standard purification methods include electrophoretic, molecular, immunological and chromatographic techniques, including ion exchange, hydrophobic, affinity, and reverse-phase HPLC chromatography, and chromatofocusmg For example, the BTRX/7 or NTR protein may be purified using a standard anti-NTR antibody column Ultrafiltration and diafiltration techniques, in conjunction with protein concentration, are also useful For general guidance in suitable purification techniques, see Scopes, R , Protein Purification, Spπnger-Verlag, NY (1982) The degree of purification necessary will vary depending on the use of the BTRX/? or NTR protein In some instances no purification will be-necessary Once expressed and purified, if necessary, the BTRX/? or NTR proteins and nucleic acids are useful in a number of applications The nucleotide sequences (or their complement) encoding BTRX/? or NTR proteins have various applications in the art of molecular biology, including uses as hybridization probes, in chromosome and gene mapping and in the generation of anti-sense RNA and DNA BTRXΛ or NTR protein nucleic acid will also be useful for the preparation of BTRX/? or NTR proteins by the recombinant techniques described herein The full-length native sequence BTRX/? or NTR protein gene, or portions thereof, may be used as hybridization probes for a cDNA library to isolate other genes (for instance, those encoding naturally- occurring, for example, allelic variants of BTRX/? or NTR protein or BTRX/? or NTR proteins from other genus or species) which have a desired sequence identity to the BTRX/? or NTR protein coding sequence Optionally, the length of the probes will be about 20 to about 50 bases The hybridization probes may be derived 'rom the nucleotide sequences herein or from genomic sequences including promoters, enhancer elements and introns of native sequences as provided herein By way of example, a screening method will comprise isolating the coding region of the BTRX/? or NTR protein gene using the known DNA sequence to synthesize a selected probe of about 40 bases Hybridization probes may be labeled by a variety of labels, including radionuclides such as 32 P or 35 S, or enzymatic labels such as alkaline phosphatase coupled to the probe via avidm/biotin coupling systems Labeled probes having a sequence complementary to that of the BTRX/? or NTR protein gene of the present invention can be used to screen libraries of human cDNA, genomic DNA or mRNA to determine to which members of such libraries the probe hybridizes Nucleotide sequences encoding a BTRX/? or NTR protein can also be used to construct hybridization probes for mapping the gene which encodes that BTRX ? or NTR protein and for the genetic analysis of individuals with genetic disorders The nucleotide sequences provided herein may be mapped to a chromosome and specific regions of a chromosome using known techniques, such as in situ hybridization, linkage analysis against known chromosomal markers, and hybridization screening with libraries Nucleic acids which encode BTRX/? or NTR protein or its modified forms can also be used to generate either transgenic plants, preferably as described above and in the Examples There are a vinety of techniques available for introducing nucleic acids mto viable cells The techniques vary depending upon whether the nucleic acid is transferred into cultured cells in vitro, or in vivo in the cells of the intended host Techniques suitable for the transfer of nucleic acid into mammalian cells in vitro include the use of liposomes, electroporation, micromjection, cell fusion, DEAE-dextran, the calcium phosphate precipitation method, microparticle bombardment (biolistic) etc The currently preferred in vivo gene transfer techniques include transfection with viral (typically retroviral) vectors and viral coat protein-liposome mediated transfection (Dzau ef al , Trends in Biotechnology 11 , 205-210 [1993]) In some situations it is desirable to provide the nucleic acid source with an agent that targets the target cells to be transformed, such as an antibody specific for a cell surface membrane protein or the target cell, a ligand for a receptor on the target cell, etc Where liposomes are employed, proteins which bind to a cell surface membrane protein associated with endocytosis may be used for targeting and/or to facilitate uptake, e g capsid proteins or fragments thereof tropic for a particular cell type, antibodies for proteins which undergo internalization in cycling, proteins that target intracellular localization and enhance intracellular half-life The technique of receptor-mediated endocytosis is described, for example, by Wu ef al , J Biol Chem 262. 4429-4432 (1987), and Wagner et al . Proc Natl Acad Sci USA 87. 3410-3414 (1990) For review of gene marking and gene therapy protocols see Anderson ef al , Science 256, 808-813 (1992) In a preferred embodiment, the BTRX 7 or NTR proteins, nucleic acids, variants, modified proteins, cells and/or transgenics containing the said nucleic acids or proteins are used in screening assays Identification of the BTRX/7 or NTR protein provided herein permits the design of screening assays for compounds that bind or modulate BTRX/? or NTR activity "Modulating the activity of a BTRX/? or NTR protein" includes an increase in activity, a decrease in activity, or a change in the type or kind of activity present Thus, in this embodiment, the candidate agent should both bind to BTRX/7 or NTR protein (although this may not be necessary), and alter its biological or biochemical activity as defined herein The methods include both in vitro screening methods, as are generally outlined above, and in vivo screening of cells for alterations in the presence, distribution, activity or amount of the BTRX ? or NTR protein Methods of assaying a biological activity of a thioredoxin h protein are known in the art Thioredoxins lack a directly measurable catalytic property that can be used in their detection and quantification Therefore, a specific companion enzyme reaction is necessary to demonstrate and measure the activity of thioredoxin proteins One of ordinary skill in the art will be aware that there are many well-established systems that can be employed to measure thioredoxm-mediated reduction of substrates See, for instance, U S Patent No 5,792,506 to Buchanan, Horecka et al (1996), Rivera-Madrid ef a/ (1995), Wong ef al (1995), Jacquot ef al (1990), Fiorencio ef al (1988), Fiorencio et al (1988), Johnson et al (1987), Schwenn and Schπek (1986), and Berstermann ef al (1983) Appropriate assay systems may be broken down into four major classes 1 ) enzyme activation (using thioredoxin to modulate another enzyme in a measurable way), 2) nbonucleotide reduction (using thioredoxin as a co-substrate by nbonucleotide reductase), 3) protein disulfide reduction (using thioredoxin for insulin A-B chain reduction) (Schwenn and Schπek, 1987), and 4) direct measurement of disulfide reduction using monobromobimane (mBBr)-derιvatιve fluorescence (Wong et al , 1995) Any such system can be used to measure thioredoxin activity Different techniques will be more or less appropriate to specific plants and tissues The appropriate technique will be determined at the discretion of the practitioner By way of example, the following techniques are appropriate for measuring the activity of thioredoxin Because of interference from other enzymes that use NADPH, the activity of thioredoxin h cannot be accurately assayed in crude plant extracts Thus, at least partial purification of the thioredoxin /? protein is necessary Such partial purification can be carried out using standard protein purification techniques, for instance (NH 4 ) 2 S0 4 extraction and column chromatography See, for example, Fiorencio ef al (1988) and Johnson ef al (1987a,b) Thioredoxin /? activity-assayable transgenic barley seed extracts can be prepared in the following manner In the embodiment, wherein Btrwh activity is assayed in a plant or plant tissue, such as a seed or grain, about fifteen grams of barley grains, may be ground ιθ powder in a coffee grinder or other like device Protein is subsequently extracted from this powder with 80 ml (1 4 w/v) of buffer (50 mM Tπs-HCI buffer, pH 7 9, 1 mM EDTA, 0 5 mM PMSF (phenylmethysulfonyl fluoride), 2 mM e-ammo-n caproic acid, 2 mM benzamidme-HCI) by stirring for three hours at 4°C The slurry plus the rinse is then subjected to centrifugation at 25,400 x g for 20 minutes, and the resultant supernatant solution decanted through glass wool The pellet is resuspended in a small volume of buffer and then clarified by centrifugation as before The two supernatant fractions are combined, an aliquot removed as a control, and the remainder subjected to acidification by adjusting the pH from about 7 83 to about 4 80 with 2 N formic acid Denatured proteins should be removed from the acidified solution by centrifugation as above prior to assaying for enzyme activity The pH of the acidified supernatant solution is then readjusted to 7 91 with 2 N NH 4 0H and an aliquot is removed for enzyme assay Powdered (NH 4 ) 2 S0 4 is added to a final concentration of 30% (w/v) and the sample stirred for 20 minutes at 4°C, followed by centrifugation as described above Additional (NH 4 ) 2 S0 4 is then added to bnng the decanted supernatant solution to 90% (w/v) saturation, and the sample stirred for 16 hours at 4°C This sample is centrifuged again as described above to yield a thioredoxin /?-ennched pellet The supernatant solution from the thioredoxin ?-enπched pellet is discarded, and the pellet re-suspended in 30 mM Tπs-HCI, pH 7 9 buffer This is then clarified by centrifugation at 40,000 x g for 15 minutes The resulting supernatant (30-50% (NH 4 ) 2 S0 4 fraction) should then be placed in dialysis tubing (6,000-8,000 MW cut-off) and exposed to solid sucrose at 4°C to obtain an approximate 10-fold reduction in volume An aliquot (about 1 ml) of the clarified and concentrated 30-90% (NH 4 ) 2 S0 4 sample should be reserved The remaining sample is applied to a pre equilibrated (30 mM Tπs-HCI, pH 7 9, 200 mM NaCl) Sephadex G-50 superfine column (2 5 x 90 cm, ~400 ml bed volume) with a peristaltic pump at a flow rate of 0 5 ml/mm Protein is eluted from the loaded column with the same buffer at the same flow rate, and 150-drop fractions collected Each fraction can be tested for thioredoxin ? activity using standard techniques, for instance the NADP-MDH activation protocol (see below) Storage of the prepared fractions should be at 4°C Thioredoxin h extracted from £ coli is stable after treatment at 60°C for 10 minutes (Mark and Richardson, 1976) Using this feature of thioredoxin h proteins, the level of background (non-thioredoxm h) enzyme activity in crude plant extracts can be decreased by heating the crude extract at 60°C for about ten minutes, using the following protocol In the example of expression of BTRX/7 in transgenic gram, approximately ten grams of, for example, barley gram are ground to powder for about 30 seconds in a coffee grinder and extracted by shaking for 1 hour at room temperature in 50 ml buffer (50 mM Tπs-HC1 buffer, pH 7 9, 1 mM EDTA, 0 5 mM PMSF, 2 mM e-amino-n caproic acid, 2 mM benzamidme-HCI) The slurry plus the rinse is then subjected to centnfugation at 27,000 x g for 20 minutes and the supernatant solution decanted through glass wool A 20 ml aliquot of the supernatant is then heated at 65°C until sample temperature reaches 60+1 °C (~10 minutes) The sample is then held at 60°C for 10 additional minutes, then cooled in an ice/water bath The cooled sample is centrifuged and the supernatant solution concentrated using solid sucrose as above The resultant heat-treated, concentrated supernatant may be stored at -20°C Frozen samples are thawed and clarified by centrifugation at 14,000 rpm for 10 minutes at 4°C Total thioredoxin h activity can then be measured in these concentrated supernatant fractions Methods and techniques of measuring thioredoxin /? activity have previously been described (see, for instance, Berstermann ef al 1983, Johnson ef al 1987, and Fiorencio ef al 1988) For each technique, about fifty to 120 μl (depending on activity) of partially purified or heat-treated plant extract as prepared above is pre-incubated with DTT, and 0 16 to 0 32 μl of this pre-mcubation mixture is then used in the assay In general, thioredoxin h activity is assayed by adding thioredoxin-beaπng sample to an NADP-thioredoxin reductase (NTR) assay system (Fiorencio ef al , 1988, Gautier ef al , 1998), and the reduction of DTNB measured Essentially, NADPH provides the reducing equivalents needed for thioredoxin reductase to reduce thioredoxin h by converting it from the disulfide (-S-S-) to the sulthydryl (-SH) form This reduced (sulthydryl) thioredoxin /? then reduces DTNB directly Reduction of DTNB is measured as an increase in absorbance of the sample at 412 nm By way of example, 1 ml reaction mixtures containing 100 μM potassium phosphate (pH 7 1), 10 μl mol @@@ 150 nmol EDTA, 150 nmol NADPH, 200 nmol DTNB (dissolved in 95% ethanol) and vaπable amounts of thioredoxin Λ-beaπng samples are initiated by the addition of 10 pmol of wheat or £ coli NTR, and the reduction of DTNB determined by monitoring the absorbance change at 412 nm The activity can then be expressed as μmol thioredoxin reduced per minute using 13,600 M 1 cm as the molar absorption coefficient of DTNB (2-SH being formed/mol reduced thioredoxin) In the NADP-Malate Dehydrogenase (MDH) Activation Assay, thioredoxin /? activity is assayed by adding thioredoxin-beaπng sample to an NADP-malate dehydrogenase (MDH) assay system (Johnson ef al , 1987, Berstermann ef al 1983) This system is similar to that used in an NADP-NTR activation assay In vitro monobromobimane (mBBr) labeling of proteins is an alternate to indirectly measuring thioredoxin h protein activity using a companion-enzyme assay, thioredoxm-mediated disulfide reduction can be measured using monobromobimane (mBBr) derivative fluorescence (Crawford ef al , 1989, Kobrehei ef al , 1992, U S Patent No 5,792,506 "Neutralization of food allergens by thioredoxin") By way of example only, the following describes an appropriate procedure as it relates to transgenic plants Immature, mature, or germinating seeds or grain from nontransformed (control) and transgenic plants are ground in 100 mM Tπs-HCI buffer, pH 7 9 Assay reactions may then be carried out essentially as described in Kobrehei ef al (1992) In general, 70 μL of the buffer mixture containing a known amount of protein is either untreated or treated with DTT to a final concentration of 0 5 mM After incubation for 20 minutes, 100 nmol of mBBr is added, and the reaction continued for another 15 minutes To stop the reaction and deπvatize excess mBBr, 10 μl of 10% SDS and 100 μl of 100 mM 2-mercaptoethanol are added The samples are then applied to a 15% SDS-PAGE gel Fluorescence of mBBr may be visualized by placing gels on a light box fitted with a UV (365 nm) light source Protein quantification can be carried out by the Bradford dye-binding method (Bradford, 1976) using, for instance, bovine serum albumin or gamma globulin as standards This protocol has been adapted for barley as described by Cho ef a/, ((1999) Proc Natl Acad Sci USA 96 14641-14646) Methods of measuring NTR activity also are known in the art In a preferred embodiment, NTR activity is determined with the DNTB assay (Fiorencio ef al , 1988) The system contains the amount of an extract, as needed, spinach thioredoxin ? (2-5 μg) and the following 100 μmol potassiuim phosphate buffer (pH 7 9) Ten μmol Na-EDTA, 0 25 μmol NADPH, 0 2 μmol DTNB The reaction is started by the addition of thioredoxin h (final volume, 1 0 ml) Increase in absorbance is followed at 412 nm The content and activity of BTRX ? and NTR is alternatively assessed by Western blot and activity measurements In the example of transgenic seeds or grains, western blots are performed on extracts selected transgenic seeds or grain as well as non-transgenic seeds or grains, including null segregants Lots of about 10-20 mtacts seeds are grains are processed and analyzed for content of BTRX/? and NTR by SDS-PAGE and western blot procedures (Cho ef al, (1999) Proc Natl Acad Sci USA 96 14641-14646) Grain or seeds extract are preferably prepared as described by Cho ef al , (1999) Plant Sci 148 9-17) Thus, in the embodiment of identifying a bioactive agent the alters a biological activity of a BTRX/? or NTR polypeptide, the methods comprise combining an BTRX/? or NTR sample and a candidate bioactive agent, and evaluating the effect on the BTRX/? or NTR activity By "BTRX/? or NTR activity" or grammatical equivalents herein is meant one of the BTRX/? or NTR protein's biological activities, including, but not limited to those described above and, for example, a BTRX/? or NTR proteins ability to alter the oxidation/reduction state of NADPH 2 or thioredoxin in vitro or in vivo Other biological activities include altering the oxidation/reduction state of a cell of a transgenic plant in which it is expressed, altering the digestibility of the starch or protein components of a transgenic seed or gram, redistribution of the proteins of a transgenic seed or gram to the more soluble albumin/globulin fraction and decreasing the allergenicity of a transgenic seed or gram In a preferred embodiment, the activity of the BTRX/7 or NTR protein is decreased, in another preferred embodiment, the activity of the BTRX/7 or NTR protein is increased Thus, bioactive agents that are antagonists are preferred in some embodiments, and bioactive agents that are agonists may be preferred in other embodiments The assays described herein preferably utilize the H vulgare BTRX/? or NTR protein, although other plant proteins may also be used, including dicotyledonous plants ( e g tomato, potato, soybean, cotton, tobacco, etc ) and monocotyledonous plants, including, but not limited to graminaceous monocots such as wheat (Tπticum spp ), rice (Oryza spp ), barley (Hordeum spp ), oat (Avena spp ), rye (Secale spp ), corn (Zea mays), sorghum (Sorghum spp ) and millet (Pennisetum spp) For example, the present invention can be employed with barley genotypes including, but not limited to Morex, Harrington , Crystal, Stander, Moravian III, Galena, Salome, Steptoe, Klages, Baronesse, and with wheat genotypes including, but not limited to Yecora Rojo, Bobwhite, Karl and Anza In general, the invention is particularly useful in cereals These latter embodiments may be preferred in the development of models of gram germination In a preferred embodiment, the methods comprise combining a BTRX/? or NTR protein and a candidate bioactive agent, and determining the binding of the candidate agent to the BTRX/7 or NTR protein In other embodiments, further discussed below, binding interference or bioactivity is determined The term "candidate bioactive agent" or "exogeneous compound" as used herein describes any molecule, e.g , protein, small organic molecule, carbohydrates (including polysacchandes), polynucleotide, lipids, etc Generally a plurality of assay mixtures are run in parallel with different agent concentrations to obtain a differential response to the various concentrations Typically, one of these concentrations serves as a negative control, i.e , at zero concentration or below the level of detection In addition, positive controls, i e the use of agents known to alter or modulate BTRX/? or NTR activity, may be used. Candidate agents encompass numerous chemical classes, though typically they are organic molecules, preferably small organic compounds having a molecular weight of more than about 100 daltons and less than about 2,500 daltons Candidate agents comprise functional groups necessary for structural interaction with proteins, particularly hydrogen bonding, and typically include at least an amme, carbonyl, hydroxyl or carboxyl group, preferably at least two of the functional chemical groups The candidate agents often comprise cyclical carbon or heterocyclic structures and/or aromatic or polyaromatic structures substituted with one or more of the above functional groups Candidate agents are also found among biomolecules including peptides, sacchaπdes, fatty acids, steroids, puπnes, pyπmidines, derivatives, structural analogs or combinations thereof Particularly preferred are peptides Candidate agents are obtained from a wide variety of sources including libraries of synthetic or natural compounds For example, numerous means are available for random and directed synthesis of a wide variety of organic compounds and biomolecules, including expression of randomized oligonucleotides. Alternatively, libraries of natural compounds in the form of bacterial, fungal, plant and animal extracts are available or readily produced Additionally, natural or synthetically produced libraries and compounds are readily modified through conventional chemical, physical and biochemical means Known pharmacological agents may be subjected to directed or random chemical modifications, such as acylation, alkylation, esterification, amidification to produce structural analogs In a preferred embodiment, a library of different candidate bioactive agents are used Preferably, the library should provide a sufficiently structurally diverse population of randomized agents to effect a probabilistically sufficient range of diversity to allow binding to a particular target Accordingly, an interaction library should be large enough so that at least one of its members will have a structure that gives it affinity for the target Although it is difficult to gauge the required absolute size of an inter- action library, nature provides a hint with the immune response a diversity of 10 7 -10 8 different antibodies provides at least one combination with sufficient affinity to interact with most potential antigens faced by an organism Published in vitro selection techniques have also shown that a library size of 10 7 to 10 8 is sufficient to find structures with affinity for the target A library of all combinations of a peptide 7 to 20 ammo acids in length, such as generally proposed herein, has the potential to code for 20 7 (10 9 ) to 20 20 Thus, with libraries of 10 7 to 10 8 different molecules the present methods allow a "working" subset of a theoretically complete interaction library for 7 ammo acids, and a subset of shapes for the 20 20 library Thus, in a preferred embodiment, at least 10 6 , preferably at least 10 7 , more preferably at least 10 β and most preferably at least 10 9 different sequences are simultaneously analyzed in the subject methods Preferred methods maximize library size and diversity In a preferred embodiment, the candidate bioactive agents are proteins By "protein" herein is meant at least two covalently attached ammo acids, which includes proteins, polypeptides, o gopeptides and peptides The protein may be made up of naturally occurring ammo acids and peptide bonds, or synthetic peptidomimetic structures Thus "am o acid", or "peptide residue", as used herein means both naturally occurring and synthetic ammo acids For example, homo-phenylalanine, citrulline and noreleucme are considered ammo acids for the purposes of the invention "Am o acid" also includes imino acid residues such as proline and hydroxyprolme The side chains may be in either the (R) or the (S) configuration In the preferred embodiment, the am o acids are in the (S) or L-configu ration If non-naturally occurring side chains are used, non-ammo acid substituents may be used, for example to prevent or retard in vivo degradations Chemical blocking groups or other chemical substituents may also be added In a preferred embodiment, the candidate bioactive agents are naturally occurring proteins or fragments of naturally occurπng proteins Thus, for example, cellular extracts containing proteins, or random or directed digests of protemaceous cellular extracts, may be used In this way libraries of procaryotic and eukaryotic proteins may be made for screening in-the systems described herein Particularly preferred in this embodiment are libraries of plant, bacterial, fungal, viral, and mammalian proteins, with the latter being preferred, and human proteins being especially preferred In a preferred embodiment, the candidate bioactive agents are peptides of from about 5 to about 30 ammo acids, with from about 5 to about 20 ammo acids being preferred, and from about 7 to about 15 being particularly preferred The peptides may be digests of naturally occurring proteins as is outlined above, random peptides, or "biased" random peptides By "randomized" or grammatical equivalents herein is meant that each nucleic acid and peptide consists of essentially random nucleotides and ammo acids, respectively Since generally these random peptides (or nucleic acids, discussed below) are chemically synthesized, they may incorporate any nucleotide or am o acid at any position The synthetic process can be designed to generate randomized proteins or nucleic acids, to allow the formation of all or most of the possible combinations over the length of the sequence, thus forming a library of randomized candidate bioactive protemaceous agents In one embodiment, the library is fully randomized, with no sequence preferences or constants at any position In a preferred embodiment, the library is biased That is, some positions within the sequence are either held constant, or are selected from a limited number of possibilities For example, in a preferred embodiment, the nucleotides or ammo acid residues are randomized within a defined class, for example, of hydrophobic ammo acids, hydrophilic residues, steπcally biased (either small or large) residues, towards the creation of cysteines, for cross-linking, pralines for SH-3 domains, seπnes, threonmes, tyros es or histidmas for phosphorylation sites, etc , or to puπnes, etc In a preferred embodiment, the candidate bioactive agents are nucleit acids By "nucleic acid" or "oligonucleotide" or grammatical equivalents herein means at least two nucleotides covalently linked together A nucleic acid of the present invention will generally contain phosphodiester bonds, although in some cases, as outlined below, nucleic acid analogs are included that may have alternate backbones, comprising, for example, phosphoramide (Beaucage, ef a/ , Tetrahedron, 49(10) 1925 (1993) and references therein, Letsinger, J Orq Chem . 35 3800 (1970), Spπnzl, et al , Eur J Biochem . 81 579 (1977), Letsinger, ef al , Nucl Acids Res . 14 3487 (1986), Sawai, et al , Chem Lett , 805 (1984), Letsinger, ef al , J Am Chem Soc . 110 4470 (1988), and Pauwels, ef al , Chemica Scπpta. 26 141 (1986)), phosphorothioate (Mag, et al , Nucleic Acids Res . 19 1437 (1991), and U S Patent No 5,644,048), phosphorodithioate (Bπu, ef al , J Am Chem Soc . 111 2321 (1989)), O- methylphophoroamidite linkages (see Eckstein, Oligonucleotides and Analogues A Practical Approach, Oxford University Press), and peptide nucleic acid backbones and linkages (see Egholm, J_ Am Chem Soc , 114 1895 (1992), Meier, ef al , Chem Int Ed Enαl . 31 1008 (1992), Nielsen, Nature. 365 566 (1993), Carlsson, ef al , Nature, 380 207 (1996), all of which are incorporated by reference)) Other analog nucleic acids include those with positive backbones (Denpcy, ef al , Proc Natl Acad Sci USA, 92 6097 (1995)), non-ionic backbones (U S Patent Nos 5,386,023, 5,637,684, 5,602,240, 5,216,141 , and 4,469,863, K,edrowshι, ef al , Anoew Chem Intl Ed English, 30 423 (1991), Letsinger, ef al , J Am Chem Soc . 110 4470 (1988), Letsinger, et al , Nucleoside &- Nucleotide, 13 1597 (1994), Chapters 2 and 3, ASC Symposium Series 580, "Carbohydrate Modifications in Antisense Research", Ed Y S Sanghui and P Dan Cook, Mesmaeker, ef al , Bioorqanic & Medicinal Chem Lett , 4 395 (1994), Jeffs, et al , J Biomolecular NMR, 34 17 (1994), Tetrahedron Lett , 37 743 (1996)) and non-πbose backbones, including those described in U S Patent Nos 5,235,033 and 5,034,506, and Chapters 6 and 7, ASC Symposium Series 580, "Carbohydrate Modifications in Antisense Research", Ed Y S Sanghui and P Dan Cook Nucleic acids containing one or more carbocychc sugars are also included within the definition of nucleic acids (see Jenkins, ef al , Chem Soc Rev , (1995) pp 169-176) Several nucleic acid analogs are described in Rawls, C & E News, June 2, 1997, page 35 All of these references are hereby expressly incorporated by reference These modifications of the πbose-phosphate backbone may be done to facilitate the addition of additional moieties such as labels, or to increase the stability and half-life of such molecules in physiological environments In addition, mixtures of naturally occurring nucleic acids and analogs can be made Alternatively, mixtures of different nucleic acid analogs, and mixtures of naturally occurring nucleic acids and analogs may be made The nucleic acids may be single stranded or double stranded, as specified, or contain portions of both double stranded or single stranded sequence The nucleic acid may be DNA, both genomic and cDNA, RNA or a hybrid, where the nucleic acid contains any combination of deoxyπbo- and πbo-nucleotides, and any combination of bases, including uracil, adenme, thymine, cytosine, guanine, mosine, xathanme hypoxathanme, isocytosme, isoguanme, etc As described above generally for proteins, nucleic acid candidate bioactive agents may be naturally occurring nucleic acids, random nucleic acids, or "biased" random nucleic acids For example, digests of procaryotic or eukaryotic genomes may be used as is outlined above for proteins In a preferred embodiment, the candidate bioactive agents are organic chemical moieties, a wide variety of which are available in the literature In a preferred embodiment, the candidate bioactive agents are linked to a fusion partner By "fusion partner" or "functional group" herein is meant a sequence that is associated with the candidate bioactive agent, that confers upon ail members of the library in that class a common function or ability Fusion partners can be heterologous (i e not native to the host cell), or synthetic (not native to any cell) Suitable fusion partners include, but are not limited to a) presentation structures, which provide the candidate bioactive agents in a conformationally restricted or stable form, b) targeting sequences, which allow the localization of the candidate bioactive agent into a subcellular or extracellular compartment, c) rescue sequences which allow the purification or isolation of either the candidate bioactive agents or the nucleic acids encoding them, d) stability sequences, which confer stability or protection from degradation to the candidate bioactive agent or the nucleic acid encoding it, for example resistance to proteolytic degradation, e) dimeπzation sequences, to allow for peptide dimeπzation, or f) any combination of a), b), c), d), and e), as well as linker sequences as needed In one embodiment of the methods described herein, portions of BTRX/7 or NTR proteins are utilized, in a preferred embodiment, portions having BTRX/? or NTR activity are used to identify agents that bind to BTRX/7 or NTR In addition, the assays described herein may utilize either isolated BTRX/? or NTR proteins or cells comprising the BTRX/? or NTR proteins Generally, in a preferred embodiment of the methods herein, for example for binding assays, the BTRX ? or NTR protein or the candidate agent is non-diffusibly bound to an insoluble support having isolated sample receiving areas (e g a microtiter plate, an array, etc ) The insoluble supports may be made of any composition to which the compositions can be bound, is readily separated from soluble material, and is otherwise compatible with the overall method of screening The surface of such supports may be solid or porous and of any convenient shape Examples of suitable insoluble supports include microtiter plates, arrays, membranes and beads These are typically made of glass, plastic (e g , polystyrene), polysacchandes, nylon or nitrocellulose, teflon™, etc Microtiter plates and arrays are especially convenient because a large number of assays can be carried out simultaneously, using small amounts of reagents and samples In some cases magnetic beads and the like are included The particular manner of binding of the composition is not crucial so long as it is compatible with the reagents and overall methods of the invention, maintains the activity of the composition and is nondiffusable Preferred methods of binding include the use of antibodies (which do not stencally block either the ligand binding site or activation sequence when the rotein is bound to the support), direct binding to "sticky" or ionic supports, chemical crosslinkmg, the synthesis of the protein or agent on the surface, etc Following binding of the protein or agent, excess unbound material is removed by washing The sample receiving areas may then be blocked through incubation with bovine serum albumin (BSA), casein or other innocuous protein or other moiety Also included in this invention are screening assays wherein solid supports are not used, examples of such are described below In a preferred embodiment, the BTRX/? or NTR protein is bound to the support, and a candidate bioactive agent is added to the assay Alternatively, the candidate agent is bound to the support and the BTRX ? or NTR protein is added Novel binding agents include specific antibodies, non-natural binding agents identified in screens of chemical libraries, peptide analogs, etc Of particular interest are screening assays for agents that have a low toxicity for human cells A wide variety of assays may be used for this purpose, including labeled in vitro protein-protein binding assays, electrophoretic mobility shift assays, immunoassays for protein binding, functional assays, preferably oxidation/reduction assays The determinatiori of the binding of the candidate bioactive agent to the BTRX/? or NTR protein may be done in a number of ways In a preferred embodiment, the candidate bioactive agent is labelled, and binding determined directly For example, this may be done by attaching all or a portion of the BTRX/? or NTR protein to a solid support, adding a labelled candidate agent (for example a radio or fluorescent label), washing off excess reagent, and determining whether the label is present on the solid support Various blocking and washing steps may be utilized as is known in the art By "labeled" herein is meant that the compound is either directly or indirectly labeled with a label which provides a detectable signal, e g radioisotope, fluorescers, enzyme, antibodies, particles such as magnetic particles, chemiluminescers, or specific binding molecules, etc Specific binding molecules include pairs, such as biotm and streptavidm, digoxm and antidigoxm etc For the specific binding members, the complementary member would normally be labeled with a molecule which provides for detection, in accordance with known procedures, as outlined above The label can directly or indirectly provide a detectable signal In some embodiments, only one of the components is labeled For example, the proteins (or protemaceous candidate agents) may be labeled at tyrosme positions using 125 l, or with fluorophores Alternatively, more than one component may be labeled with different labels, using 125 l for the proteins, for example, and a fluorophor for the candidate agents In a preferred embodiment, the binding of the candidate bioactive agent is determined through the use of competitive binding assays In this embodiment, the competitor is a binding moiety known to bind to the target molecule (i e BTRX/? or NTR protein), such as an antibody, peptide, binding partner, ligand, etc Under certain circumstances, there may be competitive binding as between the bioactive agent and the binding moiety, with the binding moiety displacing the bioactive agent This assay can be used to determine candidate agents which interfere with binding between BTRX/? or NTR proteins and binding partners "Interference of binding" as used herein means that native binding of the BTRX/? or NTR protein differs in the presence of the candidate agent The binding can be eliminated or can be with a reduced affinity Therefore, in one embodiment, interference is caused by, for example, a conformation change, rather than direct competition for the native binding site In one embodiment, the candidate bioactive agent is labeled Either the candidate bioactive agent, or the competitor, or both, is added first to the protein for a time sufficient to allow binding, if present Incubations may be performed at any temperature which facilitates optimal activity, typically between 4 and 40°C Incubation periods are selected for optimum activity, but may also be optimized to facilitate rapid high through put screening Typically between about 0 1 and about 1 0 hour will be sufficient Excess reagent is generally removed or washed away The second component is then added, and the presence or absence of the labeled component is followed, to indicate binding In a preferred embodiment, the competitor is added first, followed by the candidate bioactive agent Displacement of the competitor is an indication that the candidate bioactive agent is binding to the NTR protein and thus is capable of binding to, and potentially modulating, the activity of the NTR protein In this embodiment, either component can be labeled Thus, for example, if the competitor is labeled, the presence of label in the wash solution indicates displacement by the agent Alternatively, if the candidate bioactive agent is labeled, the presence of the label on the support indicates displacement In an alternative embodiment, the candidate bioactive agent is added first, with incubation and washing, followed by the competitor The absence of binding by the competitor may indicate that the bioactive agent is bound to the BTRX/? or NTR protein with a higher affinity Thus, if the candidate bioactive agent is labeled, the presence of the label on the support, coupled with a lack of competitor binding, may indicate that the candidate agent is capable of binding to the BTRX/? or NTR protein In a preferred embodiment, the methods comprise differential screening to identity bioactive agents that are capable of modulating the activity of the BTRX/? or NTR proteins Such assays can be done with the BTRX/? or NTR protein or cells comprising said BTRX/? or NTR protein In one embodiment, the methods comprise combining an BTRX/? or NTR protein and a competitor in a first sample A second sample comprises a candidate bioactive agent, an BTRX/? or NTR protein and a competitor The binding of the competitor is determined for both samples, and a change, or difference in binding between the two samples indicates the presence of an agent capable of binding to the BTRX/? or NTR protein and potentially modulating its activity That is, if the binding of the competitor is different in the second sample relative to the first sample, the agent is capable of binding to the BTRX/? or NTR protein Alternatively, a preferred embodiment utilizes differential screening to identify candidates that bind to the native BTRX/? or NTR protein, but cannot bind to modified BTRX/? or NTR proteins The structure of the BTRX/? or NTR protein may be modeled, and used in rational design and synthesis of agents that interact with that site Drug candidates that affect BTRX/? or NTR bioactivity are also identified by screening drugs for the ability to either enhance or reduce the activity of the protein Positive controls and negative controls may be used in the assays Preferably all control and test samples are performed in at least triplicate to obtain statistically significant results Incubation of all samples is for a time sufficient for the binding of the agent to the protein Following incubation, all samples are washed free of non-specifically bound material and the amount of bound, generally labeled agent determined For example, where a radiolabel is employed, the samples may be counted in a scintillation counter to determine the amount of bound compound A variety of other reagents may be included in the screening assays These include reagents like salts, neutral proteins, e g albumin, detergents, etc which may be used to facilitate optimal protein-protein binding and/or reduce non-specific or background interactions Also reagents that otherwise improve the efficiency of the assay, such as protease inhibitors, nuclease inhibitors, anti-microbial agents, etc , may be used The mixture of components may be added in any order that provides for the requisite binding In a preferred embodiment, the invention provides methods of screening for bioactive agents capable of modulating the activity of an BTRX ? or NTR protein The methods comprise adding a candidate bioactive agent, as defined above, to a cell comprising BTRX/? or NTR proteins Preferred cell types include almost any cell The cells contain a recombinant nucleic acid that encodes an BTRX ? or NTR protein In a preferred embodiment, a library of candidate agents are tested on a plurality of cells Detection of BTRX/? or NTR regulation may be done as will be appreciated by those in the art In one embodiment, indicators of the NTR activity are used, for example, oxidation of NADPH or reduction of thioredoxin, preferably thioredoxin h In one embodiment, indicators of the BTRX/? activity are used, for example, using the NADP-malate dehydrogenase activation assay as described by Fiorencio ef al 1988 and Johnson ef al (1987a) There are a number of parameters that may be evaluated or assayed to allow the detection of alterations in BTRX/? or NTR regulation, including, but not limited to, cell viability assays, germination characteristics of a transgenic grain or seed, redox status of transgenic gram or seed, digestibiltiy of a transgenic seed or gram, the expression of gibberellic acid induαbfe enzyme in a transgenic seed or gram Other parameters include mRNA synthesis, translation, peptides, activity of a protein or enzyme, distπbution of protein in, for example, more soluble verses less soluble fractions By assaying or measuring one or more of these parameters, it is possible to detect not only alterations in BTRX ? or NTR regulation, but alterations of different steps of the BTRX/7 or NTR regulation pathway In this manner, rapid, accurate screening of candidate agents may be performed to identify agents that modulate BTRX ? or NTR regulation Accordingly, the invention provides methods of screening for alterations in BTRX/? or NTR regulation of a population of cells By "alteration" or "modulation" (used herein interchangeably), is generally meant a change, for example, in the redox state of a substrate or co-factor of the BTRX/? or NTR protein In another embodiment, is meant a change in the redox state in a pathway affected by BTRX/? or NTR activity The measurements can be determined wherein all of the conditions are the same for each measurement, or under various conditions, with or without bioactive agents, or at different stages of the cell cycle process For example, a measurement of B TRX/? or NTR regulation can be determined in a cell or cell population wherein a candidate bioactive agent is present and wherein the candidate bioactive agent is absent In another example, the measurements of BTRX/? or NTR regulation are determined wherein the condition or environment of the cell or populations of cells differ from one another For example, the cells may be evaluated in the presence or absence or previous or subsequent exposure of physiological signals, for example hormones, antibodies, peptides, antigens, cytokmes, growth factors, action potentials, pharmacological agents including chemotherapeutics, radiation, carcmogenics, or other cells (i e cell-cell contacts) In another example, the measurements of BTRX/? or NTR regulation are determined at different stages of the cell cycle process In yet another example, the measurements of BTRX/? or NTR regulation are taken wherein the conditions are the same, and the alterations are between one cell or cell population and another cell or cell population By a "population of cells" or "library of cells" herein is meant at least two cells, with at least about 10 3 being preferred, at least about 10 6 being particularly preferred, and at least about 10 8 to 10 9 being especially preferred The population or sample can contain a mixture of different cell types from either primary or secondary cultures although samples containing only a single cell type are preferred, for example, the sample can be from a cell line, particularly tumor cell lines, as outlined below The cells may be in any cell phase, either synchronously or not, including M, G1, S, and G2 In a preferred embodiment, cells that are replicating or proliferating are used, this may allow the use of retroviral vectors for the introduction of candidate bioactive agents Alternatively, non-replicating cells may be used, and other vectors (such as adenovirus, lentivirus, and Agrobacteπum vectors) can be used In addition, although not required, the cells are compatible with dyes and antibodies Preferred cell types for use in the invention include, but are not limited to, plant cells, including mono- and dicot plants such as (cereal grains, bariey, wheat sorghum, soybeans, sugar beets, peanuts, canola and as described above), and mammalian cells, including animal (rodents, including mice, rats, hamsters and gerbils), primates, and human cells, particularly including tumor cells of all types, including breast, skin, lung, cervix, colon-rectal, leukemia, brain, etc In a preferred embodiment, the methods comprise assaying one or more of several different cell parameters, including, but not limited to, cell viability, cell proliferation, and cell phase In a preferred embodiment, cell viability is assayed, to ensure that a lack of cellular change is due to experimental conditions (i e the introduction of a candidate bioactive agent) not cell death There are a variety of suitable cell viability assays which can be used, including, but not limited to, light scattering, viability dye staining, and exclusion dye staining In a preferred embodiment, a light scattering assay is used as the viability assay, as is well known in the art For example, when viewed in the FACS, cells have particular characteristics as measured by their forward and 90 degree (side) light scatter properties These scatter properties represent the size, shape and granule content of the cells These properties account for two parameters to be measured as a readout for the viability Briefly, the DNA of dying or dead cells generally condenses, which alters the 90" scatter, similarly, membrane blebbmg can alter the forward scatter Alterations in the intensity of light scattering, or the cell-refractive index indicate alterations in viability Thus, in general, for light scattering assays, a live cell population of a particular cell type is evaluated to determine it's forward and side scattering properties This sets a standard for scattering that can subsequently be used In a preferred embodiment, the viability assay utilizes a viability dye There are a number of known viability dyes that stain dead or dying cells, but do not stain growing cells For example, annexin V is a member of a protein family which displays specific binding to phospho pid (phosphotidylseπne) in a divalent ion dependent manner This protein has been widely used for the measurement of apoptosis (programmed cell death) as cell surface exposure of phosphatidylseπne is a hallmark early signal of this process Suitable viability dyes include, but are not limited to, annexin, ethidium homodιmer-1 , DEAD Red, propidium iodide, SYTOX Green, etc , and others known in the art, see the Molecular Probes Handbook of Fluorescent Probes and Research Chemicals, Haugland, Sixth Edition, hereby incorporated by reference, see Apoptosis Assay on page 285 in particular, and Chapter 16 Protocols for viability dye staining for cell viability are Known, see Molecular Probes catalog, supra In this embodiment, the viability dye such as annexin is labeled, either directly or indirectly, and combined with a cell population Annexin is commercially available, i e , from PharMingen, San Diego, California, or Caltag Laboratoπes, Millbrae, California Preferably, the viability dye is provided in a solution wherein the dye is in a concentration of about 100 ng/ml to about 500 ng/ml, more preferably, about 500 ng/ml to about 1 μg/ml, and most preferably, from about 1 μg/ml to about 5 μg/ml In a preferred embodiment, the viability dye is directly labeled, for example, annexin may be labeled with a fluorochrome such as fluorecein isothiocyanate (FITC), Alexa dyes, TRITC, AMCA, APC, tπ-color, Cy- 5, and others known in the art or commercially available In an alternate preferred embodiment, the viability dye is labeled with a first label, such as a hapten such as biotm, and a secondary fluorescent label is used, such as fluorescent streptavidm Other first and second labeling pairs can be used as will be appreciated by those in the art Once added, the viability dye is allowed to incubate with the cells for a period of time, and washed, if necessary The cells are then sorted as outlined below to remove the non-viable cells In a preferred embodiment, exclusion dye staining is used as the viability assay Exclusion dyes are those which are excluded from living cells, i e they a-e not taken up passively (they do not permeate the cell membrane of a live cell) However, due to the permeability of dead or dying cells, they are taken up by dead cells Generally, but not always, the exclusion dyes bind to DNA, for example via intercalation Preferably, the exclusion dye does not fluoresce, or fluoresces poorly, in the absence of DNA, this eliminates the need for a wash step Alternatively, exclusion dyes that require the use of a secondary label may also be used Preferred exclusion dyes include, but are not limited to, ethidium bromide, ethidium homodιmer-1, propidium iodine, SYTOX green nucleic acid stain, Calcein AM, BCECF AM, fluorescein diacetate, TOTO® and TO-PRO™ (from Molecular Probes, supra, see chapter 16) and others known in the art Protocols for exclusion dye staining for cell viability are known, see the Molecular Probes catalog, supra In general, the exclusion dye is added to the cells at a concentration of from about 100 ng/ml to about 500 ng/ml, more preferably, about 500 ng/ml to about 1 μg/ml, and most preferably, from about 0 1 μg/ml to about 5 μg/ml, with about 0 5 μg/ml being particularly preferred The cells and the exclusion dye are incubated for some period of time, washed, if necessary, and then the cells sorted as outlined below, to remove non-viable cells from the population In addition, there are other cell viability assays which may be run, including for example enzymatic assays, which can measure extracellular enzymatic activity of either live cells (i e secreted proteases, etc ), or dead cells (i e the presence of intracellular enzymes in the media, for example, intracellular proteases, mitochondnal enzymes, etc ) See the Molecular Probes Handbook of Fluorescent Probes and Research Chemicals, Haugland, Sixth Edition, hereby incorporated by reference, see chapter 16 in particular In a preferred embodiment, at least one cell viability assay is run, with at least two different cell viability assays being preferred, when the fluors are compatible When only 1 viability assay is run, a preferred embodiment utilizes light scattering assays (both forward and side scattering) When two viability assays are run, preferred embodiments utilize light scattering and dye exclusion, with light scattering and viability dye staining also possible, and all three being done in some cases as well Viability assays thus allow the separation of viable cells from non-viable or dying cells In addition to a cell viability assay, a preferred embodiment utilizes a cell proliferation assay By "proliferation assay" herein is meant an assay that allows the determination that a cell population is either proliferating, i e replicating, or not replicating In a preferred embodiment, the proliferation assay is a dye inclusion assay A dye inclusion assay relies on dilution effects to distinguish between cell phases Briefly, a dye (generally a fluorescent dye as outlined below) is introduced to cells and taken up by the cells Once taken up, the dye is trapped in the cell, and does not diffuse out As the cell population divides, the dye is proportionally diluted That is, after the introduction of the inclusion dye, the cells are allowed to incubate for some period of time, cells that lose fluorescence over time are dividing, and the cells that remain fluorescent are arrested in a non-growth phase Generally, the introduction of the inclusion dye may be done in one of two ways Either the dye cannot passively enter the cells (e g it is charged), and the cells must be treated to take up the dye, for example through the use of a electric pulse Alternatively, the dye can passively enter the cells, but once taken up, it is modified such that it cannot diffuse out of the cells For example, enzymatic modification of the inclusion dye may render it charged, and thus unable to diffuse out of the cells For example, the Molecular Probes CellTracker™ dyes are fluorescent chloromethyl derivatives that freely diffuse into cells, and then glutathione S-transferase-mediated reaction produces membrane impermeant dyes Suitable inclusion dyes include, but are not limited to, the Molecular Probes line of CellTracker™ dyes, including, but not limited to CellTracker™ Blue, CellTracker™ Yellow-Green, CellTracker™ Green, CellTracker™ Orange, PKH26 (Sigma), and others known in the art, see the Molecular Probes Handbook, supra, chapter 15 in particular In general, inclusion dyes are provided to the cells at a concentration ranging from about 100 ng/ml to about 5 μg/ml, with from about 500 ng/ml to about 1 μg/ml being preferred A wash step may or may not be used In a preferred embodiment, a candidate bioactive agent is combined with the cells as described herein The cells and the inclusion dye are incubated for some period of time, to allow cell division and thus dye dilution The length of time will depend on the cell cycle time for the particular cells, in general, at least about 2 cell divisions are preferred, with at least about 3 being particularly preferred and at least about 4 being especially preferred The cells are then sorted as outlined below, to create populations of cells that are replicating and those that are not As will be appreciated by those in the art, in some cases, for example when screening for anti-proliferation agents, the bright (i e fluorescent) cells are collected, in other embodiments, for example for screening for proliferation agents, the low fluorescence cells are collected Alterations are determined by measuring the fluorescence at either different time points or in different cell populations, and comparing the determinations to one another or to standards In a preferred embodiment, the proliferation assay is an antimetabolite assay In general, antimetabolite assays find the most use when agents that cause cellular arrest in G1 or G2 resting phase is desired In an antimetabolite proliferation assay, the use of a toxic antimetabolite that will kill dividing cells will result in survival of only those cells that are not dividing Suitable antimetabolites include, but are not limited to, standard chemotherapeutic agents such as methotrexate, cisplatm, taxol, hydroxyurea, nucleotide analogs such as AraG, etc In addition, antimetabolite assays may include the use of genes that cause cell death upon expression The concentration at which the antimetabolite is added will depend on the toxicity of the particular antimetabolite, and will be determined as is known in the art The antimetabolite is added and the cells are generally incubated for some period of time, again, the exact period of time will depend on the characteristics and identity of the antimetabolite as well as the cell cycle time of the particular cell population Generally, a time sufficient for at least one cell division to occur In a preferred embodiment, at least one proliferation assay is run, with more than one being preferred Thus, a proliferation assay results in a population of proliferating cells and a population of arrested cells Moreover, other proliferation assays may be used, i e , colorimetπc assays known in the art In a preferred embodiment, either after or simultaneously with one or more of the proliferation assays outlined above, at least one cell phase assay is done A "cell phase" assay determines at which cell phase the cells are arrested, M, G1, S, or G2 In a preferred embodiment, the cell phase assay is a DNA binding dye assay Briefly, a DNA binding dye is introduced to the cells, and taken up passively Once inside the cell, the DNA binding dye binds to DNA, generally by intercalation, although in some cases, the dyes can be either major or minor groove binding compounds The amount of dye is thus directly correlated to the amount of DNA in the cell, which varies by cell phase, G2 and M phase cells have twice the DNA content of G1 phase cells, and S phase cells have an intermediate amount, depending on at what point in S phase the cells are Suitable DNA binding dyes are permeant, and include, but are not limited to, Hoechst 33342 and 33258, acridine orange, 7-AAD, LDS 751 , DAPI, and SYTO 16, Molecular Probes Handbook, supra, chapters 8 and 16 in particular In general, the DNA binding dyes are added in concentrations ranging from about 1 μg/ml to about 5 μg/ml The dyes are added to the cells and allowed to incubate for some period of time, the length of time will depend in part on the dye chosen In one embodiment, measurements are taken immediately after addition of the dye The cells are then sorted as outlined below, to create populations of cells that contain different amounts of dye, and thus different amounts of DNA, in this way, cells that are replicating are separated from those that are not As will be appreciated by those in the art, in some cases, for example when screening for anti-proliferation agents, cells with the least fluorescence (and thus a single copy of the genome) can be separated from those that are replicating and thus contain more than a single genome of DNA Alterations are determined by measuring the fluorescence at either different time points or in different cell populations, and comparing the determinations to one another or to standards In a preferred embodiment, the ceil phase assay is a cyclin destruction assay In this embodiment, prior to screening (and generally prior to the introduction of a candidate bioactive agent, as outlined below), a fusion nucleic acid is introduced to the cells The fusion nucleic acid comprises nucleic acid encoding a cyclin destruction box and a nucleic acid encoding a detectable molecule "Cyclin destruction boxes" are known in the art and are sequences that cause destruction via the ubiquitmation pathway of proteins containing the boxes during particular cell phases That is, for example, G1 cyclms may be stable during G1 phase but degraded during S phase due to the presence of a G1 cyclin destruction box Thus, by linking a cyclin destruction box to a detectable molecule, for example green fluorescent protein, the presence or absence of the detectable molecule can serve to identify the cell phase of the cell population In a preferred embodiment, multiple boxes are used, preferably each with a different fluor, such that detection of the cell phase can occur A number of cyclin destruction boxes are known in the art, for example, cyclin A has a destruction box comprising the sequence RTVLGVIGD (SEQ ID NO 34A), the destruction box of cyclin B1 comprises the sequence RTALGDIGN (SEQ ID NO 35) See Glotzer et al , Nature 349 132-138 (1991) Other destruction boxes are known as well YMTVSIIDRFMQDSCVPKKMLQLVGVT (SEQ ID NO 36, rat cychn B), KFRLLQETMYMTVSIIDRFMQNSCVPKK (SEQ ID NO 37, mouse cyclin B), RAILIDWLIQVQMKFRLLQETMYMTVS (SEQ ID NO 38, mouse cyclin B1 ), DRFLQAQLVCRKKLQWGITALLLASK (SEQ ID NO 39, mouse cyclin B2), and MSVLRGKLQLVGTAAMLL (SEQ ID NO 40, mouse cyclin A2) The nucleic acid encoding the cyclin destruction oox is operably linked to nucleic acid encoding a αetectable molecule The fusion proteins are constructed by methods known in the art For example, the nucleic acids encoding the destruction box is ligated to a nucleic acid encoding a detectable molecule By "detectable molecule" herein is meant a molecule that allows a cell or compound comprising the detectable molecule to be distinguished from one that does not contain it, i e , an epitope, sometimes called an antigen TAG, a specific enzyme, or a fluorescent molecule Preferred fluorescent molecules include but are not limited to green fluorescent protein (GFP), blue fluorescent protein (BFP), yellow fluorescent protein (YFP), red fluorescent protein (RFP), and enzymes including lu ferase and β-galactosidase When antigen TAGs are used, preferred embodiments utilize cell surface antigens The epitope is preferably any detectable peptide which is not generally found on the cytoplasmic membrane, although in some instances, if the epitope is one normally found on the cells, increases may be detected, although this is generally not preferred Similarly, enzymatic detectable molecules may also be used, for example, an enzyme that generates a novel or chromogenic product Accordingly, the results of sorting after cell phase assays generally result in at least two populations of cells that are in different cell phases The proteins and nucleic acids provided herein can also be used for screening purposes wherein the piotein-protem interactions of the BTRX/? or NTR proteins can be identified Genetic systems have been described to detect protein-protein interactions The first work was done in yeast systems, namely the "yeast two-hybrid" system The basic system requires a protein-protein interaction in order to turn on transcription of a reporter gene Subsequent work was done in mammalian cells See Fields et al , Nature 340 245 (1989), Vasavada et al , PNAS USA 88 10686 (1991), Fearon et al , PNAS USA 89 7958 (1992), Dang et al , Mol Cell Biol 11 954 (1991), Chien et al , PNAS USA 88 9578 (1991), and U S Patent Nos 5,283,173, 5,667,973, 5,468,614, 5,525,490, and 5,637,463 a preferred system is described in Serial Nos 09/050,863, filed March 30, 1998 and 09/359,081 filed July 22, 1999, entitled "Mammalian Protein Interaction Cloning System" For use in conjunction with these systems, a particularly useful shuttle vector is described in Serial No 09/133,944, filed August 14, 1998, entitled "Shuttle Vectors" In general, two nucleic acids are transformed into a cell, where one is a "bait" such as the gene encoding an BTRX/? or NTR protein or a portion thereof, and the other encodes a test candidate. Only if the two expression products bind to one another will an indicator, such as a fluorescent protein, be expressed. Expression of the indicator indicates when a test candidate binds to the BTRX/? or NTR protein and can be identified as an BTRX/7 or NTR protein. Using the same system and the identified BTRX/? or NTR proteins the reverse can be performed. Namely, the BTRX/7 or NTR proteins provided herein can be used to identify new baits, or agents which interact with BTRX/? or NTR proteins. Additionally, the two-hybrid system can be used wherein a test candidate is added in addition to the bait and the BTRX/? or NTR protein encoding nucleic acids to determine agents which interfere with the bait and the BTRX/7 or NTR protein interactions. In one embodiment, a mammalian two-hybrid system is preferred. Mammalian systems provide post- translational modifications of proteins which may contribute significantly to their ability to interact. In addition, a mammalian two-hybrid system can be used in a wide variety of mammalian cell types to mimic the regulation, induction, processing, etc. of specific proteins within a particular cell type. For example, proteins involved in a disease state (i.e., cancer, apoptosis related disorders) could be tested in the relevant disease cells. Similarly, for testing of random proteins, assaying them under the relevant cellular conditions will give the highest positive results. Furthermore, the mammalian cells can be tested under a variety of experimental conditions that may affect intracellular protein-protein interactions, such as in the presence of hormones, drugs, growth factors and cytokines, radiation, chemotherapeutics, cellular and chemical stimuli, etc., that may contribute to conditions which can effect protein-protein interactions, particularly those involved in cancer. Assays involving binding such as the two-hybrid system may take into account non-specific binding proteins (NSB). Expression in various cell types, and assays forBTRX/7 or NTR activity are described above. The activity assays, such as having an effect on, for example, the oxidation/reduction state of a cell or cell component, organelle, or molecule performed to confirm the activity of BTRX/7 or NTR proteins which have already been identified by their sequence identity/similarity or binding to BTRX/? or NTR as well as to further confirm the activity of lead compounds identified as modulators of BTRX/? or NTR. In one embodiment, the BTRX ? or NTR proteins of the present invention may be used to generate polyclonal and monoclonal antibodies to BTRX/? or NTR proteins, which are useful as described herein. Similarly, the BTRX/? or NTR proteins can be coupled, using standard technology, to affinity chromatography columns. These columns may then be used to purify BTRX/? or NTR antibodies. In a preferred embodiment, the antibodies are generated to epitopes unique to the NTR protein; that is, the antibodies show little or no cross-reactivity to other proteins. These antibodies find use in a number of applications For example, the BTRX/? or NTR antibodies may be coupled to standard affinity chromatography columns and used to purify BTRX/? or NTR proteins as further described below The antibodies may also be used as blocking polypeptides, as outlined above, since they will specifically bind to the BTRX/7 or NTR protein The anti-NTR protein antibodies may comprise polyclonal antibodies Methods of preparing polyclonal antibodies are known to the skilled artisan Polyclonal antibodies can be raised in a mammal, for example, by one or more injections of an immunizing agent and, if desired, an adjuvant Typically, the immunizing agent and/or adjuvant will be injected in the mammal by multiple subcutaneous or mtrapeπtoneal injections The immunizing agent may include the BTRX/? or NTR protein or a fusion protein thereof It may be useful to conjugate the immunizing agent to a protein known to be immunogenic in the mammal being immunized Examples of such immunogenic proteins include but are not limited to keyhole limpet hemocyanin, serum albumin, bovine thyroglobulm, and soybean trypsm inhibitor Examples of adjuvants which may be employed include Freund's complete adjuvant and MPL-TDM adjuvant (monophosphoryl Lipid a, synthetic trehalose dicorynomycolate) The immunization protocol may be selected by one skilled in the art without undue experimentation The anti-Btrxh or anti-NTR protein antibodies may, alternatively, be monoclonal antibodies Monoclonal antibodies may be prepared using hybπdoma methods, such as those described by Kohler and Milstem, Nature, 256 495 (1975) In a hybπdoma method, a mouse, hamster, or other appropriate host animal, is typically immunized with an immunizing agent to elicit lymphocytes that produce or are capable of producing antibodies that will specifically bind to the immunizing agent Alternatively, the lymphocytes may be immunized in vitro The immunizing agent will typically include the BTRX/7 or NTR protein or a fusion protein thereof Generally, either peripheral blood lymphocytes ("PBLs") are used if cells of human origin are desired, or spleen cells or lymph node cells are used if non-human mammalian sources are desired The lymphocytes are then fused with an immortalized cell line using a suitable fusing agent, such as polyethylene glycol, to form a hybπdoma cell [Godmg, Monoclonal Antibodies Principles and Practice. Academic Press, (1986) pp 59-103] Immortalized cell lines are usually transformed mammalian cells, particularly myeloma cells of rodent, bovine and human origin Usually, rat or mouse myeloma cell lines are employed The hybπdoma cells may be cultured in a suitable culture medium that preferably contains one or more substances that inhibit the growth or survival of the unfused, immortalized cells For example, if the parental cells lack the enzyme hypoxanthme guanine phosphoπbosyl transferase (HGPRT or HPRT), the culture medium for the hybπdomas typically will include hypoxanthme, aminopteπn, and thymidine ("HAT medium"), which substances prevent the growth of HGPRT-deficient cells Preferred immortalized cell lines are those that fuse efficiently, support stable high level expression of antibody by the selected antibody-producing cells, and are sensitive to a medium such as HAT medium More preferred immortalized cell lines are murine myeloma lines, which can be obtained, for instance, from the Salk Institute Cell Distribution Center, San Diego, California and the American Type Culture Collection, Rockville, Maryland Human myeloma and mouse-human heteromyeloma cell lines also have been described for the production of human monoclonal antibodies [Kozbor, J_ Immunol . 133 3001 (1984), Brodeur et al , Monoclonal Antibody Production Techniques and Applications, Marcel Dekker, Ine , New York, (1987) pp 51-63] The culture medium in which the hybridoma ceils are cultured can then be assayed for the presence of monoclonal antibodies directed against NTR protein Preferably, the binding specificity of monoclonal antibodies produced by the hybridoma ceils is determined by immunoprecipitation or by an in vitro binding assay, such as radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA) Such techniques and assays are known in the art The binding affinity of the monoclonal antibody can, for example, be determined by the Scatchard analysis of Munson and Pollard, Anal Biochem , 107 220 (1980) After the desired hybridoma cells are identified, the clones may be subcloned by limiting dilution procedures and grown by standard methods [Godmg, supral Suitable culture media for this purpose include, for example, Dulbecco's Modified Eagle's Medium and RPMI-1640 medium Alternatively, the hybπdoma ceils may be grown in vivo as ascites in a mammal The monoclonal antibodies secreted by the subclones may be isolated or purified from the culture medium or ascites fluid by conventional immunoglobulin purification procedures such as, for example, protein a-Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography The monoclonal antibodies may also be made by recombinant DNA methods, such as those described in U S Patent No 4,816,567 DNA encoding the monoclonal antibodies of the invention can be readily isolated and sequenced using conventional procedures (e g , by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of murine antibodies) The hybridoma cells of the invention serve as a preferred source of such DNA Once isolated, the DNA may be placed into expression vectors, which are then transfected into host cells such as simian COS cells, Chinese hamster ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin protein, to obtain the synthesis of monoclonal antibodies in the recombinant host cells The DNA also may be modified, for example, by substituting the coding sequence for human heavy and light chain constant domains in place of the homologous murine sequences [U S Patent No 4,816,567, Morrison et al , supral or by covalently joining to the immunoglobulin coding sequence all or part of the coding sequence for a non-immunoglobuiin polypeptide Such a non- immunoglobuiin polypeptide can be substituted for the constant domains of an antibody of the invention, or can be substituted for the variable domains of one antigen-combining site of an antibody of the invention to create a chimeric bivalent antibody The antibodies may be monovalent antibodies Methods for preparing monovalent antibodies are well known in the art For example, one method involves recombinant expression of immunoglobulin light chain and modified heavy chain The heavy chain is truncated generally at any point in the Fc region so as to prevent heavy chain crosslinkmg Alternatively, the relevant cysteine residues are substituted with another ammo acid residue or are deleted so as to prevent crosslinkmg In vitro methods are also suitable for preparing monovalent antibodies Digestion of antibodies to produce fragments thereof, particularly, Fab fragments, can be accomplished using routine techniques known in the art The anti-NTR protein antibodies of the invention may further comprise humanized antibodies or human antibodies Humanized forms of non-human (e g , murine) antibodies are chimeric immunoglobulins, immunoglobulin chains or fragments thereof (such as Fv, Fab, Fab', F(ab') 2 or other antigen-binding subsequences of antibodies) which contain minimal sequence derived from non- human immunoglobulin Humanized antibodies include human immunoglobulins (recipient antibody) in which residues from a complementary determining region (CDR) of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat or rabbit having the desired specificity, affinity and capacity In some instances, Fv framework residues of the human immunoglobulin are replaced by corresponding non-human residues Humanized antibodies may also compπse residues which are found neither in the recipient antibody nor in the imported CDR or framework sequences In general, the humanized antibody will comprise substantially ail of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin consensus sequence The humanized antibody optimally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin [Jones et al , Nature. 321 522-525 (1986), Riechmann et al , Nature. 332 323-329 (1988), and Presta, Curr Op Struct Biol . 2 593-596 (1992)] Methods for humanizing non-human antibodies are well known in the art Generally, a humanized antibody has one or more am o acid residues introduced into it from a source which is non-human These non-human ammo acid residues are often referred to as "import" residues, which are typically taken from an "import" variable domain Humanization can be essentially performed following the method of Winter and co-workers [Jones et al , Nature. 321 522-525 (1986), Riechmann et al , Nature, 332 323-327 (1988), Verhoeyen et al , Science, 239 1534-1536 (1988)], by substituting rodent CDRs or CDR sequences for the corresponding sequences of a human antibody Accordingly, such "humanized" antibodies are chimeric antibodies (U S Patent No 4,816,567), wherein substantially less than an intact human variable domain has been substituted by the corresponding sequence from a non-human species In practice, humanized antibodies are typically human antibodies in which some CDR residues and possibly some FR residues are substituted by residues from analogous sites in rodent antibodies Human antibodies can also be produced using various techniques known in the art, including phage display libraries [Hoogenboom and Winter, J Mol Biol . 227 381 (1991), Marks et al , J Mol Biol , 222 581 (1991)] The techniques of Cole et al and Boerner et al are also available for the preparation of human monoclonal antibodies (Cole et al , Monoclonal Antibodies and Cancer Therapy. Alan R ϋss, p 77 (1985) and Boerner et al , J Immunol . 147(1) 86-95 (1991)] Similarly, human antibodies can be made by introducing of human immunoglobulin loci into transgenic animals, e g , mice in which the endogenous immunoglobulin genes have been partially or completely inactivated Upon challenge, human antibody production is observed, which closely resembles that seen in humans in all respects, including gene rearrangement, assembly, and antibody repertoire This approach is described, for example, in U S Patent Nos 5,545,807, 5,545,806, 5,569,825, 5,625,126, 5,633,425, 5,661 ,016, and in the following scientific publications Marks ef al , Bio/Technology 10, 779-783 (1992), Lonberg ef al , Nature 368 856-859 (1994), Morrison. Nature 368. 812-13 (1994), Fishwild ef al . Nature Biotechnology 14. 845-51 (1996), Neuberger, Nature Biotechnology 14. 826 (1996), Lonberg and Huszar, Intern Rev Immunol 13 65-93 (1995) Bispecific antibodies are monoclonal, preferably human or humanized, antibodies that have binding specificities for at least two different antigens In the present case, one of the binding specificities is for the NTR protein, the other one is for any other antigen, and preferably for a cell-surface protein or receptor or receptor subunit Methods for making bispecific antibodies are known in the art Traditionally, the recombinant production of bispecific antibodies is based on the co-expression of two immunoglobulin heavy- chain/light-chain pairs, where the two heavy chains have different specificities [Milstem and Cuello, Nature, 305 537-539 (1983)] Because of the random assortment of immunoglobulin heavy and light chains, these hybπdomas (quadromas) produce a potential mixture of ten different antibody molecules, of which only one has the correct bispecific structure The purification of the correct molecule is usually accomplished by affinity chromatography steps Similar procedures are disclosed in WO 93/08829, published 13 May 1993, and in Traunecker et al , EMBO J , 10 3655-3659 (1991 ) Antibody variable domains with the desired binding specificities (antibody-antigen combining sites) can be fused to immunoglobulin constant domain sequences The fusion preferably is with an immunoglobulin heavy-chain constant domain, comprising at least part of the hinge, CH2, and CH3 regions It is preferred to have the first heavy-chain constant region (CH1) containing the site necessary for light-chain binding present in at least one of the fusions DNAs encoding the immunoglobulin heavy-chain fusions and, if desired, the immunoglobulin light chain, are inserted into separate expression vectors, and are co-transfected into a suitable host organism For further details of generating bispecific antibodies see, for example, Suresh et al , Methods in Enzymoloqy. 121 210 (1986) Heteroconjugate antibodies are aiso within the scope of the present invention Heteroconjugate antibodies are composed of two covalently joined antibodies Such antibodies have, for example, been proposed to target immune system cells to unwanted cells [U S Patent No 4,676,980], and for treatment of HIV infection [WO 91/00360, WO 92/200373, EP 03089] It is contemplated that the antibodies may be prepared in vitro using known methods in synthetic protein chemistry, including those involving crosslinkmg agents For example, immunotoxms may be constructed using a disulfide exchange reaction or by forming a thioether bond Examples of suitable reagents for this purpose include iminothiolate and methyl-4-mercaptobutyπmιdate and those disclosed, for example, in U S Patent No 4,676,980 The anti-NTR protein antibodies of the invention have various utilities For example, anti-NTR protein antibodies may be used in diagnostic assays for a NTR protein, e g , detecting its expression in specific cells or tissues etc Various diagnostic assay techniques known in the art may be used, such as competitive binding assays, direct or indirect sandwich assays and immunoprecipitation assays conducted in either heterogeneous or homogeneous phases [Zola, Monoclonal Antibodies a Manual of Techniques, CRC Press, Ine (1987) pp 147-158] The antibodies used in the diagnostic assays can be labeled with a detectable moiety The detectable moiety should be capable of producing, either directly or indirectly, a detectable ignal For example, the detectable moiety may be a radioisotope, such as 3 H, 14 C, 32 P, ^S, or 125 l, a fluorescent or chemiluminescent compound, such as fluorescein isothiocyanate, rhodam e, or lucifenn, or an enzyme, such as alkaline phosphatase, beta- galactosidase or horseradish peroxidase Any method known in the art for conjugating the antibody to the detectable moiety may be employed, including those methods described by Hunter et al , Nature, 144 945 (1962), David et al , Biochemistry. 13 1014 (1974), Pain et al , J Immunol Meth . 40 219 (1981), and Nygren, J Histochem and Cvtochem . 30 407 (1982) Anti-Btrxh or anti-NTR protein antibodies also are useful for the affinity purification of BTRX/? or NTR protein from recombinant cell culture or natural sources In this process, the antibodies against NTR protein are immobilized on a suitable support such a Sephadex resm or filter paper, using methods well known in the art The immobilized antibody then is contacted with a sample containing the BTRX/? or NTR protein to be purified, and thereafter the support is washed with a suitable solvent that will remove substantially all the material in the sample except the BTRX ? or NTR protein, which is bound to the immobilized antibody Finally, the support is washed with another suitable solvent that will release the BTRX/? or NTR protein from the antibody III. Use of Plants Expressing Elevated Levels of Thioredoxin and/or NTR In one embodiment, the transgene protein, for example BTRX/? or NTR transgene expressed in plants (see for example USSN 60/126,736), especially seeds or grains, using the methods described herein, is used in the production and synthesis of BTRX/? or NTR The BTRX/? or NTR transgene expressed by the recombinant nucleic acid of the invention may be harvested at any point after expression of the protein has commenced When harvesting from the seed or grain or other part of a plant for example, it is not necessary for the seed or gram or other part of the plant to have undergone maturation prior to harvesting For example, transgene expression may occur prior to seed or gram maturation or may reach optimal levels prior to seed or grain maturation The transgene protein may be isolated from the seeds or gram, if desired, by conventional protein purification methods For example, the seed or grain can be milled, then extracted with an aqueous or organic extraction medium, followed by purification of the extracted thioredoxin protein Alternatively, depending on the nature of the intended use, the transgene protein may be partially purified, or the seed or grain may be used directly without purification of the transgene protein for food processing or other purposes The overexpression of the BTRX/? or NTR either alone or, preferably in combination, in a seed of gram increases the redox status (SH SS ratio) of the seed or grain The combination can be achieved by, for example, breeding plants individually transformed with either BTRX/? or NTR, co-transformation with BTRX ? and NTR expression vectors, or by mixing the products of the individually transformed plants In a preferred embodiment, the transgenic seed or grains of the invention find use in the production of food or feed products with increased digestibility, decreased allergeniαty, a redistribution of the protein of a seed or gram to the more soluble faction For example, the addition of thioredoxin promotes the formation of a protein network that produces flour with enhanced baking quality Kobrehei ef al , (1994) have shown that the addition of thioredoxin to flour of non-glutenous cereal such as rice, maize, and sorghum promotes the formation of a doughlike product Accordingly, the addition of thioredoxin expressed in seeds using the methods described herein find use in the production of flour with improved baking quality such as increased strength and/or volume The enhanced expression of thioredoxin also produces a seed having an altered biochemical composition For example, enhanced thioredoxin expression produces seed with increased enzymatic activity, such as, increased pullulanase and alpha-amylase A Enhanced thioredoxin expression also produces seed with early alpha-amylase B activation Pullulanase ("debranchmg enzyme") is an enzyme that breaks down branched starch of the endosperm of cereal seeds by hydrolytically cleaving alpha-1 ,6 bonds Alpha-amylases break down starch 1-4 linkages Pullulanase and amylases are enzymes fundamental to the brewing and baking industries Pullulanase and amylases are required to break down starch in malting and in certain baking procedures carried out in the absence of added sugars or other carbohydrates Obtaining adequate activity of these enzymes is problematic especially in the malting industry It has been known for some time that dithiothreitol (DTT, a chemical reductant that reduces and sometimes replaces thioredoxin) activates pullulanase of cereal preparations (e g , barley, oat, and rice flours) A method of adequately increasing the activity of pullulanase d.id alpha-artfylase A and shortening the activation time of alpha-amylase B with a physiologically acceptable system, leads to more rapid malting methods and, owing to increased sugar availability, to alcoholic beverages such as beers with reduced carbohydrate content Accordingly, seeds or grains with enhanced thioredoxin expression provide advantages in the production of malt and beverages produced by a fermentation process Enhanced pullulanase and alpha-amylase A and earlier induction of alpha-amylase B in gram increases the speed and efficiency of germination, important in malting, where malt is produced having increased enzymatic activity resulting in enhanced hydrolysis of starch to fermentable carbohydrates, thereby, improving the efficiency of fermentation in the production of alcoholic beverages, for example, beer and scotch whiskey Early alpha-amylase B activation would reduce the total time for malting by about 20% Enhanced fermentation processes also find use in the production of alcohols that are not intended for human consumption, i e , industrial alcohols In another embodiment, seed or grains with enhanced thioredoxin expression provide advantages in enhancing the onset and efficiency of germination The overexprassion of thioredoxin in seed or grains results in an increase in the total protein It also promotes the redistribution of proteins to the most soluble albumin/globulin fraction and the production of flour and other food products, feed, and beverages with improved digestibility in comparison to edible products made from non-transformed grains Such edible products find use in amelioration and treatment of food malabsorptive syndromes, for example, sprue or catarrhal dysentery Sprue is a malabsorptive syndrome affecting both children and adults, precipitated by the mgestion of gluten- contaming foods Edible products that are more readily digested and readily absorbed avoid or ameliorate the disease symptoms Edible products with improved digestibility also ameliorate or reduce symptoms associated with celiac disease in which storage proteins that are not readily digested in afflicted individuals result in inflammation of the Gl tract The expression of thioredoxin in seed grams results in the production of foods and other edible products with reduced allergenicity in comparison to edible products made from non-transformed grains Food allergies are a significant health and nutrition problem (Lehrer ef al , 1996) Up to 2% of adults and 8% of children have a food allergy causing serious symptoms including death Wheat protein is one of the principal allergens Food allergies are defined by the American academy of Allergy and Immunology Committee on Adverse Reactions to Food as "an immunological reaction resulting from the gestion of a food or a food additive" (Fenema, 1996, Lasztity, 1996) Most true allergic responses to food proteins appear to be caused by a type-l immunoglobulin E (IgE)-medιated hypersensitivity reaction (Sicherer, 1999) These responses may occur within minutes or a few hours after eating the offending food (Furlong-Munoz, 1996) When the offending food is ingested by allergy-sensitive ιndιvιdι.als the body releases histamines and other biochemicals, resulting in itchy eyes, rash or hives, runny nose, swelling of the lips, tongue, and face, itching or tightness of the throat, abdominal pain, nausea, diarrhea, and shortness of breath Some individuals have severe, anaphylactic reactions, resulting in approximately 135 deaths per year in the United States In the U.S over 2,500 emergency rooms visits per year are allergy-related There is no cure for food allergies, only avoidance of the food will prevent symptoms For example, patients with wheat allergy must avoid wheat- or gluten-containing foods, wheat gluten is a very common ingredient in many processed foods (Marx ef al , 2000) A feature common to many allergens is the presence of one or more disulfide bonds that contribute to the resistance of allergens to digestion (Astwood et al , 1996), allowing them to be mostly intact when they react the small intestine where they are presented to mucosal cells that mount an IgE immune response The major allergens were found to be insoluble storage proteins, gliadms and giutenms The soluble storage proteins, albumins and globulins were considerably weaker (Buchanan ef al , 1997) Allergenicity of these proteins is substantially decreased after thioredoxin treatment and disulfide bond reduction Edible products, for example, bread, cookies, dough, thickeners, beverages, malt, pasta, food additives, including animal feeds, made using the transgenic plants or parts of a transgenic plant of the invention have decreased allergenicity and accordingly can be used to in the treatment of an allergic response By "treatment" or "alleviating" symptoms herein is meant prevention or decreasing the probability of symptoms Increased digestibility of seeds or grains also provides wider consumption of grains by man and animals who otherwise can not consume such grains For example, sorghum is the world's fifth leading gram in terms of metric tons after wheat, rice, maize, and barley and third in production in the Untied States after maize and wheat The use of sorghum is constrained in part because of the difficulty associated with the digestibility of its protein and starch compared to other grains This difficulty with the digestibility of sorghum protein and starch has to do with the structure of the seed and the manner in which the proteins are associated with the starch The digestibility of the starch flour from sorghum cultivars is 15-25% lower in digestibility than, for example, maize Perhaps more notable is the fact that, unlike other grains, the indigestibiiity of unprocessed sorghum flour increases dramatically after boiling in water, a common practice in Africa A study with human subjects showed that protein digestibility in cooked sorghum porridge can be as low as 46%, whereas the percent digestibility for cooked wheat, maize, and rice was 81%, 73%, and 66% respectively (Mertz ef al 1984, MacLean ef al 1981) Exogenous addition of reducing agents increases the digestibility of the starch (Hamaker et al 1987) HoweverJhe efficacy of manipulating the thioredoxin system in vivo in the seed by expressing increased amounts of thioredoxin in a manner which does not adversely affect plant development or morphology had not previously been demonstrated Accordingly, the transgenic plants of the invention provide wider use of seeds or grains as food sources by increasing the digestibility of the starch and/or protein component The transgenic seeds or grams of the present invention also provide the advantage of increasing the digestibility of food products for human and feed for animals made of these grains without the addition of exogenous reducing agents In addition, the increased digestibility results in greater utilization of the food or feed, i e , a human or animal consuming an edible product comprising a transgenic seed or gram of the invention or an extract thereof more efficiently absorbs nutrients and therefore requires to consume less in comparison to a non-transgenic food product In another embodiment the transgenic seed, gram or extracts thereof of the present invention and extracts or food products thereof are used as a food or feed additives For example, an extract or flour or malt produced from a transgenic seed or gram of the invention is added to a non-transgenic food or feed product to improve the digestibility or decrease the allergenicity of the nontransgenic food product or to improve the quality of the total food product, such as, by increasing the strength and/or volume of the food product Illustrative embodiments of the invention are described below, EXAMPLES Example 1 Barley Gene for Thioredoxin /? Barley thioredoxin /? was cloned using PCR with primers derived from the known sequences of two thioredoxin h wheat genes (Gautier ef al , 1998) When these two sequences were compared, conserved ammo acid regions were found The following primers were prepared that hybridized to these regions wtrh4 5'-CCAAGAAGTTCCCAGCGTC-3' (SEQ ID NO 7) wtrh2R 5'-CACGCGGCGGCCCAGTAA-3' (SEQ ID NO 8) These primers were used in an amplification reaction essentially as described by Sambrook ef al (1989) A scutellum bariey (Hordeum vulgare L ) cDNA library was used as template The resultant PCR product, corresponding to part of the barley thioredoxin h sequence highly homologous to the wheat cDNAs (Figure 2), was gel-purified using QIAquick Gel extraction kit (Quiagen, UK) and sequenced using an automated sequencer (Perken Elmer, CA, USA) This amplification product was then used to build a gene-specific probe according to a random priming protocol (Promega, Madison, Wl, USA) using 32 P-dCTP The synthesized probe was purified with a TE Midi Select-D, 650 column (5 Prιme-3 Prime, ine , CO, USA), and used to screen the barley scutellum λZapll cDNA library Plaques were transferred onto nitrocellulose filters (NitroPure, MSI, Westboro, MA, USA) by standard methods (Sambrook ef al , 1989) The DNA was fixed onto the filters using a Stratalmker UV crosslinkmg apparatus (Stratagene, La Jolla, CA, USA) and prehybπdized for 3 5 hours at 55°C in a MKII Mini Oven (Hybaid, Woodπdge, NJ, USA) using a solution containing 6 x SSC, 10mM EDTA, 5X Denhardt's solution, 0 5% SDS and 100 ug/ml of boiled calf thymus DNA (Sambrook ef al , 1989) Hybridization was carried out at 68°C for 15 hours with 30 ul of the barley thioredoxin h probe-solution per hybridization Blots were washed twice in 2 x SSC, 0 1% SDS at room temperature for 30 minutes, twice in 1 x SSC, 0 1% SDS at 65°C for 30 minutes, and once in 0 1 x SSC, 0 1% SDS, then exposed to X-ray film at -70°C with two intensifying screens for 18 hours Hybridizing plaques were isolated separately using a Pasteur pipette and resuspended in 500 μl SM (Sambrook ef al , 1989) with 20 μl chloroform in an Eppendorf tube The samples were then vortexed for two minutes and stored at 4°C overnight The phage suspension was diluted so that approximately 100 plaques were contained on each 100 mm plate (one cored plaque in 1 ml SM buffer represents about 0 10 6 pfu (plaque forming unιt(s), Lambda Zapll Library Instruction Manual, Stratagene, La Jolla, CA) Two positive clones per 20,000 plaque-forming units (pfu) were found After a second screening purification, the size of the insert in the positive clones was determined using the T3 and T7 primers which hybridize to the extremities of the λ Zapll polylinker site Two 1 5 kb fragments were obtained Sequencing revealed that these two clones contained the same full-length thioredoxin h cDNA The full-length barley thioredoxin h cDNA is 369 bp (Figure 2) and encodes a protein of MW 13,165 Daltons (Figure 1) with a theoretical pi of 5 12 It shares homology with the Arabidopsis and wheat thioredoxin /? cDNAs, but is unique in its nucleic and ammo acid sequences The putative corresponding ammo acid sequence contains the conserved thioredoxin active site (Figure 1) The bariey ammo acid and cDNA sequences are homologous to known wheat thioredoxins h sequences (Figures 1 and 2) Nevertheless, the alanine enriched ammo-terminal region is shorter in the barley thioredoxin /? (by 5 ammo acids compared to pTaM1338 (accession number X69915) and by 8 ammo acids compared to pTd14132 (accession number AJ001903) (Figure 1)) Example 2 Nucleotide Seguence of a cDNA Encoding an NADP-Thioredoxm Reductase (NTR) from Barley (Hordeum vulaare L ) A cDNA library from barley (Hordeum vulgare L , cv Himalaya) scutellum tissues was constructed by in λ Zap II (Stratagene, La Jolla, CA) from poly(A)+ RNA The cDNA library was screened by PCR using a set of degenerate pnmers, mRNTR2 (5'-TTCTTCGCSATCGGMCAYGARCC-3\ SEQ ID NO 13) plus mRNTR5R (5'-GCGTCSARRGCRGCCATGCASCC-3\ SEQ ID NO 14), producing the internal 201 -bp fragment It was re-screened using a set of primers, MPNTR7 (5'-ACSACSACSACSGACGTSGARAA-3\ SEQ ID NO 15) plus BNTR9R (5'-ACTGGTATGTGTAGAGCCC-3\ SEQ ID NO 16), producing the internal 693-bp fragment (Figure 3) The sequences of 5'- and 3'-cDNA ends with cDNA library were obtained by PCR using primer sets, T3 (5'-MπMCCCTCACTAAAGGG-3', SEQ ID NO 17) plus E TR12R (5'- AAGTTCTCGACGTCGGTGGTG-3', SEQ ID NO 18) and M13R (5'-CAGGAAACAGCTATGAC-3', SEQ ID NO 19) plus BNTR10 (5'-ATTATGCAGGCTAGGGCGCTC-3', SEQ ID NO 20), respectively A full-length barley scutellum NTR cDNA clone was amplified by PCR using a primer set, BNTR22 (5'- TATCTAGAATGGAGGGATCCGCCGCGGCGC-3', SEQ ID NO 21) plus BNTR23R (5'- TTGGTACCTCAATCAGACTTGCCCACCTGT-3', SEQ ID NO 22), was subcloned into the pActl INosKmf(-) vector at the Xόal-Kpnl sites and the PCR-amplified NTR sequence was then identified by DNA sequencing analysis The barley scutellum NTR cDNA clone has an open reading frame (ORF) of 332 ammo acids (SEQ ID NO 23) (Figure 5A-B, Table 1 ) The calculated molecular weight determined for the translation product of that ORF was 34,900 daltons and the predicted PI is 6 03 (Tabie 1 ) The bariey scutellum deduced am o acid sequence has 71% similarity with the A thaliana NTR (SEQ ID NO 24) and 39% with £ coli NTR (SEQ ID NO 25) (Figure 4B) using the CLUSTAL-V method set at default parameters (Higgins and Sharp (1989) Comput Appl BIOSCI , 5(2) 151-153). A gene tree analysis suggested that the sequence of H vulgare NTR is more closely related to that of A thaliana NTR than £ coli NTR (Figure 4C). Figures 5A and 5B show the nucleotide sequence of the barley scutellum NTR (SEQ ID NO 10) isolated from a cDNA library At the nucleotide level, H vulgare NTR shows 58% similarity to A thaliana NTR (SEQ ID NO 26) and 41% to £ coli NTR (SEQ ID NO 27) (Figure 5C) as determined by CLUSTAL-V default parameters Shaded residues in Figure 5B indicate nucleotide sequences conserved in all three NTR genes from H vulgare, A thaliana and £ coli Table 1 Predicted Structural Class of the Whole Protein Alpha Deleage & Roux Modification of Nishikawa and Ooι (1987) 1 microgram ; 28.654 pMoles Molar Extinction Coefficient 27910 ±5% 1 A(280) 1.25 mg/ml Isoelectric Point 6.03 Charge ay pH 7 -4.05 Whole Protein Composition Analysis: Amino Acid(s) Number Count % by Weight % by Frequency Charged (R, K, H, Y, C, D, E) 81 31.07 24.40 Acidic (D, E) 33 11.53 9.94 Basic (K, R) 28 11.57 8.43 Polar (N, C, Q, S, T, Y) 80 25.05 24.10 Hydrophobic (A, I, L, F, W, V) 127 36.67 38.25 A Ala 44 8.96 13.25 CCys 5 1.48 1.51 D Asp 17 5.61 5.12 EGIu 16 5.92 4.82 FPhe 14 5.90 4.22 GGIy 37 6.05 11.14 HHis 7 2.75 2.11 I He 17 5.51 5.12 KLys 12 4.41 3.61 LLeu 19 6.16 5.72 M et 7 2.63 2.11 N Asn 11 3.60 3.31 P Pro 12 3.34 3.61 QGIn 11 4.04 3.31 RArg 16 7.16 4.82 SSer 21 5.24 6.33 TThr 24 6.95 7.23 VVal 30 8.52 9.04 WTrp 3 1.60 0.90 YTyr 8 3.74 2.41 B Asx 0 0.00 0.00 ZGIx 1 0.37 0.30 XXxx 0 0.00 0.00 Example 3 Expression of Wheat thioredoxin h (WTRXh) in Transgenic Barley Four different DNA constructs were produced, each containing a 384-bp wtrxh fragment encoding the 13 5-KDa WTRXh protein The four constructs are illustrated in Figure 6 and described below Each construct comprised the 384-bp wtrxh fragment operably linked to a seed-specific promoter (either the barley endosperm-specific D-hordein or B1 -hordein promoters or the maize embryo-specific globulin promoter) An additional construct comprised the 384-bp wtrxh fragment operably linked to the B1 -hordein promoter and the B1 -hordein signal sequence (Figure 6) The transformation vector used included the bar gene, conferring resistance to bialaphos Twenty-eight independent regenerable barley lines were obtained after bialaphos selection and all were PCR-positive for the bar gene The presence of the wtrxh gene was confirmed in the genome of the 28 independent lines by PCR and DNA hybridization analyses The expression of the WTRXh protein was assessed by western blot analysis, using purified wheat thioredoxin as a control The WTRXh expressed in transgenic barley had a molecular mass that differed from native barley TRXh but was identical to WTRXh The WTRXh was found to be highly expressed in developing and mature seed of transgenic barley plants although levels of expression varied among the transgenic events On average, higher expression levels were observed in lines transformed with the DNA construct containing the B1 -hordein promoter plus the signal peptide sequence than the same promoter without the signal peptide sequence The WTRXh purified from transgenic barley seed was confirmed to be biochemically active A. Materials and Methods Plant Materials for Transformation A two-rowed spring cultivar of barley, Golden Promise, was grown in growth chambers as described previously (Wan and Lemaux 1994, Lemaux ef al , 1996) Construction of Wheat Thioredoxin h Expression Vectors and DNA Sequencing Expression vectors were constructed containing the wheat thioredoxin h gene (wtrxh) driven by the barley endosperm-specific B1- or D-hordein promoter or the maize embryo-specific globulin promoter The plasmids were constructed as follows (1) pDhWTRXN-2 A 384-bp wtrxh coding region was amplified by PCR from pTaM13 38 (Gautier ef al , 1998) This plasmid contained a cDNA of wtrxh, which was used as a template, creating Xbal and Sad sites with the following primers Wtrxhl (5'-atatctaqaATGGCGGCGTCGGCGGCGA) (SEQ ID NO 28) and Wtrxh2R (5'-atagagctcTTACTGGGCCGCGTGTAG) (SEQ ID NO 29), respectively (Figure 6) Small letters in the primer denote a restriction enzyme site for subcloning of the DNA fragment containing the wtrxh gene, underlined letters denote wtrxh sequences The ATG initiation codon for wtrxh expression was included in the Wtrxhl primer PCR reactions were performed on a thermocycler (MJ Research Ine , Watertown, MA) using recombinant Taq DNA polymerase (Promega Madison, Wl) in a 100-μl reaction volume The reaction buffer contained 10 mM Tπs-HCI (pH 9 0), 50 mM KCI, 1 5 mM MgCI 2 , 0 1% Tπton-X-100, and 50 μM of each deoxyπbonucleoside tπphosphate PCR conditions utilized 25 cycles of 94°C for 1 m , 55°C for 1 mm and 72°C for 2 mm, with a final extension step at 72°C for 7 mm The wtrxh fragment, which was amplified with the primers Wtrxhl and Wtrxh2R, was purified from a 0 7% agarose gel using a QIAquick ® gel extraction kit (Qiagen Ine , Chatsworth, CA), digested with Xbal and Sacl and ligated into Xbal/Sacl-digested pUC19 to generate the pWTRXh-1 plasmid Nucleotide sequences of the PCR-amplified wtrxh coding region fragment were determined by the dideoxynucleotide chain termination method using Sequenase according to manufacturer's instructions (United States Biochemical, Cleveland, OH) with double-stranded plasmid templates and regularly spaced primers pDhWTRXN-2 was made by replacing the uidA gene in pDhGN-2 (containing barley endosperm-specific D-hordein promoter (Figure 12) and nos 3' terminator) with the Xbal/Sacl fragment containing the wtrxh coding sequence from pWTRXh- 1, which contains the PCR-amplified wtrxh coding sequence in pUC19 To construct pDhGN-2, a 0 4-kb D-hordein promoter was amplified by PCR from pDI l-Hor3 (Sørenson ef al , 1989, 1996, Cho ef al , 1999a) This plasmid contained the D- hordem promoter sequence, which was used as a template, creating Sph\ and Xba\ sites with the following pπmers Dhorl (5'-ggcgcatgcgaattcGAATTCGATATCGATCTTCGA-3') (SEQ ID NO.30) and Dhor2 (5'-aactctagaCTCGGTGGACTGTCAATG-3') (SEQ ID NO 31), respectively Small letters in the primers contain restriction enzyme sites for subcloning of the DNA fragment containing the D-hordein promtoer, underlined letters denote D-hordein promoter sequences The PCR amplified D-hordein promoter fragment was digested with Sph\ and Xbal and repalced with the cauliflower mosaic 35S (CaMV 35S) promoter in p35SGN-3 to generate the pDhGN-2 plasmid p35SGN-3 was made by ligatmg the 3 0-kb Sph\-EcoR\ fragment containing the CaMV 35S promoter, uidA (beta-glucuronidase, gus) gene and nos into the Spftl/EcoRI-digested pUC18 (2) pdBhWTRX-1 The construction of pdBhWTRXN-1 started by using pBhWTRXN-1 pBhWTRXN-1 was made by replacing the uidA gene in pBhGN-1 , which contains uidA driven by the barley endosperm-specific B1-hordeιn promoter and terminated by the nos 3' terminator, with the Xbal/Sacl fragment from pWTRXh-1 , which contains the wtrxh coding sequence The 120-bp Hιndlll-5' B1 -hordein flanking region was deleted from the pBhWTRXN-1 and religated to make the pdBhWTRXN-1 construct (3) pdBhssWTRXN3-8 Primers Bhor7 (5'-GTAAAGCITTAACAACCCACACATTG) (SEQ ID NO 7) and BhorWtrxM R (5'-CCGACGCCGCTGCAATCGTACTTGTTGCCGCAAT) (SEQ ID NO 8) containing Hindlll and Acyl sites, respectively, were used for amplification of a 0 49-kb B1-hordeιn 5'-regιon, which included the B1 -hordein signal peptide sequence (Figure 11) A λ2-4/Hιndlll plasmid containing a genomic clone of B1 -hordein (Brandt ef al , 1985, Cho and Lemaux, 1997) was used as a template for the amplification The primer BhorWtrxhl R is an overlapping primer, which contains the wtrxh coding sequence (underlined) and a partial signal peptide sequence from the B1-hordeιn promoter, but lacks the ATG initiation codon for wtrxh pdBhssWTRXN3-8 was made by replacing the D-hordein promoter (Figure 6) in pDhWTRXN-2 with the 0 49-kb PCR-amplified Hindlll/Acyl fragment, which contains the B1 -hordein promoter, its signal peptide sequence and the junction region from the 5' trxh gene Thus, construct pdBhssWTRXN3-8 contains the barley endosperm-specific B1-hordeιn promoter with its signal peptide sequence (Figure 6), wtrxh ,and nos (Figure 6) The signal peptide sequence containing the ATG initiation codon was directly combined with the sequence of wtrxh, with no extra ammo acid sequences being introduced between the two This ensures that the WTRXh protein has a precise cleavage site in the lumen of the endoplasmic reticulum (ER) The authenticity of a PCR-amplified fragment from the chimeric product was confirmed by DNA sequencing (4) pGlbl WTRXN-1 The 1 42-kb Hindlll/BamHI fragment containing the maize embryo-specific globulin promoter from the ppGlblGUS plasmid (Liu and Kπz, 1996) was ligated into pBiuescπpt II KS(+) to create Hindlll and Xbal sites pGlbWTRXN-1 was made by restricting pDhWTRXN-2 with Hindlll and Xbal in order to remove the 0 49-kb H dlll/Xbal barley D-hordein promoter from the pDhWTRXN-2 In place of the 0 49-kb Hmdlll/Xbal D-hordein promoter fragment (Figure 6), the 1 42-kb Hmdlll/.Xbal maize globulin promoter was ligated into the Hmdlll/Xbal digested pDhWTRXN-2 to form the pGlbWTRXN-1 plasmid Stable Barley Transformation Stable transgenic lines of barley expressing WTRXh driven by the B1-hordeιn promoter with and without the signal peptide sequence (Figure 11), by the D-hordein promoter (Figure 12) and by the maize globulin promoter were obtained following modifications of published protocols (Wan and Lemaux 1994, Lemaux ef al , 1996, Cho ef al , 1998a-c) Whole immature embryos (lEs) ( 1 0-2 5 mm) were aseptically removed, placed scutellum-side down on DC callus-induction medium containing 2 5 mg/L 2,4-D and 5 μM CuS0 4 (Cho ef al , 1998a-c) One day after incubation at 24±1°C in the dark, the lEs were transferred scutellum-side up to DC medium containing equimolar amounts of mannitol and sorbitol to give a final concentration of 0 4 M Four hours after treatment with the osmoticum, the lEs were used for bombardment Gold particles (1 0 μm) were coated with 25 μg of a 1 1 molar ratio of pAHC20 (Chπstensen and Quail, 1996) and one of the following plasmids, pdBhWTRXN-1 , pdBhssWTRXN3-8, pDhWTRXN-2 and pG1bWTRXN-1 The microprojectiles were bombarded-usmg a PDS-1000 He biolistic device (Bio-Rad, Ine , Hercules, CA) at 1100 psi Bombarded lEs were selected on DC medium with 5 mg/L bialaphos for 2 to 3 months Bialaphos-resistant callus was transferred onto an intermediate cultuπng medium (DBC2, Cho ef al , 1998a-c), containing 2 5 mg/L 2,4-D, 0 1 mg/L BAP and 5 0 μM CuS04, between the selection [DC medium plus bialaphos (Meiji Seika Kaisha, Ltd , Yokohama, Japan)] and regeneration (FHG medium, Hunter, 1988) steps The cultuπng after callus induction and selection on DC medium were carried out under dim light conditions (approximately 10 to 30 μE, 16 h- ght) (Cho ef al , 1998a-c) Regenerated shoots were transferred to Magenta boxes containing rooting medium (callus-induction medium without phytohormones) containing 3 mg/L bialaphos When shoots reached the top of the box, plantlets were transferred to soil in the greenhouse Cytolo ical Analysis For cytological analysis of transgenic barley plants healthy root meπstems were collected from young plants grown in the greenhouse After pre-treatment at 4°C in saturated 1-bromonaphthalene solution overnight, root meπstems were fixed in 1 3 glacial acetic acid ethanol and stored at 4°C Root meπstems were hydrolyzed in 1 M HCl at 60° C for 5-7 mm, stained in Feulgen solution and squashed on a glass slide in a drop of 1% aceto-carmine Chromosomes were counted from at least five well-spread cells per plant Herbicide Application To determine herbicide sensitivity of T 0 plants and their progeny, a section of leaf blade at the 4- to 5-leaf stage was painted using a cotton swab with 0 25% (v/v) Basta™ solution (starting concentration 200 g/L phophinothπcin, Hoechst AG, Frankfurt, Germany) plus 0 1% Tween 20 Plants were scored 1 week after herbicide application Polymerase Chain Reaction (PCR) and DNA Blot Hybndization Total genomic DNA from leaf tissues was purified as described by Dellaporta (1993) To test for the presence of wtrxh in genomic DNA of putatively transformed lines, 250 ng of genomic DNA was amplified by PCR using one of two primer sets Set 1 Wtrxhl (5'-ATATCTAGAATGGCGGCGTCGGCGGCGA) (SEQ ID NO 28) and Wtrxh2R (5'-ATAGAGCTCTTACTGGGCCGCGTGTAG) (SEQ ID NO 29), or Set 2 Wtrxh4 (5'-CCAAGAAGTTCCCAGCTGC) (SEQ ID NO 32) and WtrxhδR (5'-ATAGCTGCGACAACCCTGTCCTT) (SEQ ID NO 33) The presence of bar was determined using the primer set BAR5F (δ'-CATCGAGACAAGCACGGTCAACTTCS') (SEQ ID NO 34) and BAR1R (5'-ATATCCGAGCGCCTCGTGCATGCG) (SEQ ID NO 35) (Lemaux et al , 1996) Amplifications were performed with Taq DNA polymerase (Promega, Madison, Wl) in a 25-μl reaction (Cho ef al , 1998a-c) Twenty-five microliters of the PCR product with loading dye were subjected to electrophoresis in a 1 0% agarose gel with ethidium bromide and photographed using exposure to UV light Presence of 0 4- and 0 14-kb fragments was consistent with intact and truncated wtrxh fragments, respectively, an internal 0 34-kb fragment was produced from the bar gene with bar primers Homozygous lines for wtrxh were screened by PCR and western blot analysis in T 2 or T 3 plants For DNA hybridization analysis, 10 μg of total genomic DNA from leaf tissue of each line was digested with Hindlll and Saci, separated on a 1 0% agarose gel, transferred to Zeta-Probe GT membrane (Bio-Rad, Hercules, CA) and hybridized with a radiolabeled wfrx/7-specιfic probe following the manufacturer's instructions The wfrx/7-contaιnιng 04 kb Xbal-Sacl fragment from pDhWTRXN-9 was purified by QIAEX gel extraction kit (QIAGEN, Chatsworth, CA) and labeled with 32 P-dCTP using random primers Western Blot Analysis Western blot analysis was performed on seeds from selected transgenic lines as well as from control barley seeds from non-transgenic Golden Promise grown under the same conditions as the transgenic plants and from control wheat seeds of a durum wheat cultivar, cv Monroe, or a bread wheat cultivar cv Capitale Whole seeds were ground to a fine powder with a mortar and pestle under liquid nitrogen Ten to 20 seeds were used for each sample, the volume of extraction buffer (50 mM Tπs HCl or phosphate buffer, pH 7 8, 0 5 mM phenylmethyl sulfonyl fluoride [PMSF], 1 mM EDTA) varied from 2 to 4 ml depending on the number of seeds used and the viscosity of the extract Grinding was continued for an additional minute after buffer addition, the mixture was then centrifuged at 14,000xg for 10 minutes and the supernatant solution was saved as the albumin-globulin fraction that contained the thioredoxin SDS-PAGE of the albumin-globulin fraction was performed in 12-17% polyacrylamide gradient gels at pH 8 5 (Laemmli, 1970) From each sample equal amounts of protein (-40 μg) quantitated according to Bradford (1976) were diluted 1 2 v/v in Laemmli sample buffer, boiled for 3 minutes, loaded onto gels and subjected to electrophoresis at a constant current of 15 mA Proteins were transferred to nitrocellulose at a constant voltage of 40 V for 4 hours at 4°C using a Hoefer Transphor Transfer Unit (Alameda, CA) Nitrocellulose was blocked with 5% powdered milk in TBS for 2 hours at room temperature (RT), incubated in primary antibody for 4 hours at RT and in secondary antibody for 1 hour at RT Primary antibody was wheat anti-thioredoxm h II Ab (Johnson ef al , 1987b) diluted 1 to 500, secondary antibody was goat anti-rabbit alkaline phosphatase (Bio-Rad, Hercules CA) diluted 1 3000 Blots were developed in NBT/BCIP alkaline phosphatase color reagent (according to Bio-Rad instructions), gels were stained with Coomassie blue to assure transfer Images were scanned using a Bio-Rao GelDoc 1000 (Hercules, CA) and analyzed using Bio-Rad Multi Analyst, version 1 0 2 All bands were scanned over the same area, using a rectangle of comparable density as background, results were expressed as % of volume scanned The number shown represents the percent of the total volume (pixel density X area of scanned band) WTRXh Activity Measurements Preparation of Materials for Extraction Mature grains from various heterozygous and homozygous transgenic lines served as starting materials for the assay Heterozygous lines with a D-hordein promoter were GPDhBarWtrx-5, GPDhBarWtrx-9-1 , and GPDhBarWtrx-9-2 Heterozygous lines with a B-hordem promoter and no signal sequence were GPdBhBarWtrx-2, -5, -9, -19 and GPdBhBarWtrx-20 Heterozygous lines with a B-hordein promoter plus a signal sequence were GPdBhssBarWtrx-2, -7, GPdBhssBarWtrx-29, GPdBhssBarWto<-20, GPdBhssBarWtrx-14, GPdBhssBarWtrx-22 Homozygous lines with a signal sequence were GPdBhssBarWtrx-2-17, GPdBhssBarWtrx-2-17-1 , GPdBhssBarWtrx-29-3 and GPdBhssBarWtrx-29-3-2 Control materials included a non-transformed tissue culture derived line, 4-96, a transformed line containing only bar, GPBar-l, and null segregant lines, GPdBhssBarWtrx-29-11 and GPdBhssBarWtrx-29-11-10, derived from line GPdBhssBarWtrx-29 Preparation of (NH ^ SO, Extracts for Gel Filtration Approximately fifteen grams of barley grains were ground to powder in a coffee grinder and extracted with 80 ml (1 4 w/v) of buffer [(50 mM Tπs-HCI buffer, pH 7 9, 1 mM EDTA, 0 5 mM PMSF (phenylmethysulfonyl fluoride)], 2 mM e-ammo-π caproic acid, 2 mM benzamidme-HCI) by stirring for 3 hrs at 4°C The slurry plus the rinse was subjected to centrifugation at 25,400xg for 20 mm, the supernatant solution was decanted through glass wool, pellets were resuspended in a small volume of buffer and then clarified by centrifugation as before The supernatant fractions were combined, an aliquot was removed and the remainder was subjected to acidification by adjusting the pH from 7 83 to 4 80 with 2 N formic acid, denatured proteins were removed by centrifugation as above prior to assay The pH of the acidified supernatant solution was readjusted to 7 91 with 2 N NH 4 OH and an aliquot was removed for assay Powdered (NH 4 ) 2 S0 4 was added to a final concentration of 30% and the sample was stirred for 20 m at 4°C, followed by centrifugation as described above The pellet was discarded Additional (NH 4 ) 2 S0 4 was added to bring the decanted supernatant solution to 90% saturation, the sample was stirred for 16 hrs at 4°C, followed by centrifugation as described above The supernatant solution was discarded, the 30-90% (NH 4 ) 2 S0 4 pellets were re-suspended in 30 mM Tπs-HCI, pH 7 9 buffer and then subjected to centrifugation at 40,000xg for 15 mm to clarify The resulting supernatant (30-90% (NH 4 ) 2 S0 4 fraction) was added to dialysis tubing (6,000-8,000 MW cut-off) and exposed to solid sucrose at 4°C to obtain a 10-fold reduction in volume An aliquot (1 ml) of the clarified and concentrated 30-90% (NH 4 ) 2 S0 4 ) sample was saved and the remaining sample was applied to a pre-equilibrated (30 mM Tπs-HCI, pH 7 9, 200 mM NaCl) Sephadex G-50 superfine column (2.5 x 90 cm, ~400 mL bed volume) with a peristaltic pump at a flow rate of 0 5 mlJmin Protein was eluted with the same buffer at the same flow rate, one hundred fifty drop-fractions were collected Selected fractions were used to measure absorbance at 280 nm using a Pharmacia Biotech Ultrospec 4000 and to assay for TRX/? activity following the NADP-MDH activation protocol (see below)- Active fractions were pooled, stored at 4°C, and then assayed for total NADP-MDH activation activity Preparation of Heat-Treated Extracts Approximately 10 grams of barley grains were ground to powder for about 30 sec in a coffee grinder and extracted by shaking for 1 hr at room temperature in 50 mL buffer as above The slurry plus the rinse was subjected to centrifugation at 27,000xg for 20 mm and the supernatant solution decanted through glass wool A 20 mL aliquot of each sample was heated at 65°C until sample temperature reached 60±1°C (-10 mm) The sample was held at 60°C for 10 additional mm, followed by cooling in an ice/water bath The cooled sample was centrifuged and the supernatant solution was concentrated by sucrose as above and stored at -20°C Frozen samples were thawed and clarified by centrifugation at 14,000 rpm for 10 mm at 4°C Total TRXh activity was estimated on the concentrated, supernatant fractions NADP-Malate Dehydrogenase Activation Assay Thioredoxin /? activity was assayed as previously described (Fiorencio ef al , 1988, Johnson ef al , 1987a) Fifty to 120 μl of extract (depending on activity) was premcubated with DTT, and 0 16 to 0 32 μl of the pre-mcubation mixture was used for the NADP-MDH assay Control assays were conducted on identical fractions in the absence of NADP-MDH Western blot analysis was conducted as described above except that 10 to 20 % SDS-polyacrylamide gels were used for electrophoresis and transfer to nitrocellulose paper was for 4 hrs at 40 V Sequential Extraction of Multiple Protein Fractions Ten grams of barley gram were sequentially extracted for albumin (H 2 0-soluble), globulin (salt-soluble), hordems (alcohol-soluble) and glutelms (Shewry ef al , 1980) Barley powder was stirred with 0 5 M NaCl for 1 h at 25°C to remove salt-soluble proteins Two sequential hordein fractions were extracted from the residue with 50% propanol in the absence (hordeιn-l) and presence (hordem-ll) of 2% (v/v) 2- mercaptoethanol Glutelms were extracted from the residue with 0 05 M borate buffer, pH 10, containing 1% (v/v) 2-mercaptoethanol and 1% (v/v) sodium dodecylsulphate In vitro Monobromobimane (mBBr) Labeling of Proteins Immature, mature, or germinating seeds from nontransformed and transgenic plants were ground in 100 mM Tπs-HCI buffer, pH 7 9 Reactions were carried out following the protocol of Kobrehei ef al , (1992) Seventy microliters of the buffer mixture containing a known amount of protein was either untreated or treated with DTT to a final concentration of 0 5 mM After incubation for 20 mm, 100 nmol of mBBr was added, and the reaction was continued for another 15 mm To stop the reaction and derivatize excess mBBr, 10 μl of 10% SDS and 100 μl of 100 mM 2-mercaptoethanol were added The samples were applied to a 15% SDS-PAGE gel Fluorescence of mBBr was visualized by placing gels on a light box fitted with a UV light source (365 nm) Protein determination was carried out by the Bradford dye binding method (Bradford 1976) using bovine serum albumin or gamma globulin as standards Assay of Pullulanase and its Inhibitor To measure pullulanase activity, gram was germinated in a dark chamber and retained for up to 5 days at 25°C as described (Kobrehei ef al , 1992 , Lozano ef a/ , 1996 ) A set of plates from each line was removed for extract preparation each day Cell-free endosperm extracts were prepared from lots of 10- 20 germinated grains of equivalent root and coleoptile length within a given cohort Endosperm was separated from the embryo and other tissues and added to Tπs-HCI buffer (50 mM, pH 7 9) supplemented with 1 mM EDTA and 0 5 mM PMSF (1 3 to 1 6, wt vol ratio of tissue to buffer depending on developmental stage) After grinding in a mortar on ice, the sample was clarified by centrifugation (10 mm at 24,000xg), the supernatant fraction was recovered and stored in 0 5-ml aliquots -80°C for pullulanase spectrophotometπc or gel assays Pullulanase activity was determined spectrophotometπcally at 37°C by measuring dye released after 30 mm at 534 nm using red pullulan (Megazyme, Bray, Ireland) as substrate in 50 mM citrate- phosphate buffer (pH 5 2) (Serre ef al , 1990 ) Pullulanase also was assayed on native activity gels of 7 5% acrylamide, 1 5 mm thickness, containing 1% red pullulan (Furegon et al , 1994 ) Gels were scanned using a Bio-Rad Gel Doc 1000 and analyzed using Bio-Rad ULTI ANALYST, version 1 0 2 Pullulanase inhibitor activity was determined on fractions heated to inactivate pullulanase (70°C for 15 mm) by measuring their ability to inhibit added purified barley malt pullulanase Endogenous pullulanase activity was shown to be completely eliminated by this heat-treatment while the inhibitor activity was not affected (Macπ ef al , 1993, MacGregor ef al , 1994) Alpha-Amylase Activity in Barley Grain Overexpressmg Thioredoxin h Amylase activity from the null segregant and homozygous barley grains was analyzed during germination and early seedling growth by using gels containing starcfi Native polyacrylamide electrophoresis gels [6% acrylamide, 1 5 mm thick] were prepared and developed according to the method of Laemmli (1970) except that SDS was omitted from all solutions The separating gel contained 0 5% soluble starch (Lintner potato starch, Sigma Chemical Co , St Louis, MO) Lyophilized samples were dissolved in distilled H 2 0 and mixed 1 1 with a buffer consisting of 0 25 M Tπs-HCI, pH 6 8, 50% glycerol, 0 04% bromophenol blue, and 3 mM CaCI 2 Fifty micrograms of sample protein were loaded in each lane Electrophoresis was carried out at 80 milliamps per gel at 4°C until the dye front was at the edge of the gel (usually 4 to 5 hours) After electrophoresis, the gels were incubated in 100 ml of 0 1 M succmate buffer, pH 6 0, for 1-2 hours at 37°C The gels were then stained for 5 mm in a solution containing 2 5 mM l 2 and 0 5 M Kl Gels were washed in distilled H 2 0 Except for the white regions containing amylase activity, gels were stained dark blue Isoelectncfocusmg (IEF) For determination of alpha-amylase isozyme patterns, extracts from both dry and germinating gram of transformed and control (untransformed) bariey were separated by electrophoresis at 4°C [1 0 mm thick, pH 3-10 isoelectπc focusing (IEF) polyacrylamide gels, using the X cell II system (NOVEX, San Diego, CA)] Cathode buffer contained 20 mM arginme, and 20 mM lysine, anode buffer was 7 mM phosphoric acid Samples were mixed 1 1 and 2x IEF sample buffer pH 3-10 (NOVEX) Aftersample application (20 μg/lane) gels were developed at constant voltage [100 V for 1 hr, 200 V for an additional 1 hr, and 500 V for 30 mm] IEF standards (Bio-Rad) were used to determine the pH gradient of the gels Multiple Antibody Probing of IEF Gels Western blot analysis of alpha-amylase isozymes was performed using a Mini Trans-Blot Electrophoretic Transfer Cell (Bio-Rad) Seed extracts from the null segregant and homozygous lines overexpressmg wheat thioredoxin h were separated by IEF gels as described above Proteins were transferred to nitrocellulose at a constant voltage of 100 V for 1 hr at 4°C using 0 75% acetic acid as blotting buffer Nitrocellulose was blocked with 5% powdered milk in Tπs buffer solution (20 mM Tπs- HCl, pH 7 5, supplemented with 0 15 M NaCl) for 1 hr at room temperature incubated with primary antibody for 4 hours at room temperature and then with secondary antibody for 1 hour at room temperature Primary antibody was anti-barley alpha-amylase B diluted 1 1000, secondary antibody was goat anti-rabbit alkaline phosphatase (Bio-Rad) diluted 1 3000 Blots were developed in NBT/BCIP alkaline phosphatase color reagent (according to Bio-Rad instructions) thereby rendering the cross-reacted alpha-amylase bluish-purple To achieve full identity of isozyme pattern, blots were probed a second time with another primary antibody, anti-alpha-amylase A (diluted 1 1000) and the secondary antibody (as above) This time blots were developed in Naphthol Phosphate/Fast Red alkaline phosphatase color reagent (according to Bio-Rad instructions) which gave a pink stain to the alpha-amylase A The blot shown was subject to this dual probing procedure B. Results and Discussion Production of Transgenic Plants One day after bombardment, the whole embryos were transferred onto DC medium with 5 mg/L bialaphos At transfer to the second selection plate (5 mg/L bialaphos), all material from individual callusing embryos was broken into small pieces (2-4 mm) using forceps and maintained separately During the subsequent two to five selection passages on 5 mg/L bialaphos (at 10- 20 d intervals) callus pieces showing evidence of more vigorous growth were transferred to new selection plates During the second round of selection, some pieces of callus were inhibited in growth and in some cases pieces turned brown In general, transformed tissues were observed after three or more rounds of selection The bialaphos-resistant tissues were transferred onto an intermediate medium, DBC2 or DBC3 (Cho ef al , 1998a-c) with bialaphos (5mg/L), and grown for 1 to 2 months before regeneration on FHG medium containing 3 mg/L bialaphos Green plantlets were transferred into Magenta boxes containing 3 mg/L bialaphos Twenty-eight independent putatively transformed, regenerable lines were produced after bialaphos selection (shown in Table 3) Table 3 Transgenic Barley Lines Transformed with Wheat Thioredoxin h Gene *n d not determined Analysis of T n Plants and their Progeny PCR analysis was performed using two sets of WTRXh primers and one set of BAR primers (see Figure 6) PCR amplification resulted in 0 4-kb intact wtrxh or 0 14kb truncated wtrxh and 0 34-kb internal bar fragments from transgenic lines Of the 28 lines tested, 28 yielded bar fragments from T 0 leaf tissue and 26 produced PCR-amplified fragments for wtrxh, giving a 93% co-transformation frequency Nine lines were transformed with pdBhWTRXN-1 , eleven with pdBhssWTRXN-8, five with pDhWTRXN-2 and one with pG1bWTRXN-1 (see Table 2) Three lines (GPdBhBarWtrx-5, GPdBhssBarWtrx-21 and GPDhBarWtrx-22) were sterile Seeds of T, plants and their progeny from selected wfrx/7-posιtιve lines were planted in order to screen for homozygous lines Homozygous lines and null segregants were obtained from GPdBhssBarWtrx-2, -29 and GPDhBarWtrx-9 (see Table 2) Cvtolooical Analysis of Transgenic Plants Chromosomes were counted in root meπstem cells of independently transformed T 0 barley plants Out of 28 independent transgenic lines examined 17 lines had the normal diploid chromosome complement (2n=2x=14), while the remaining 11 lines were tetraploid (2n=4x=28) (see Table 2) Characterization and Content of WTRXh Produced in Transgenic Seed As discussed above, several stably transformed barley lines were obtained that express wheat thioredoxin h As seen in Figure 7, the stable introduction of the wtrxh linked to the B1 -hordein promoter with the signal peptide sequence resulted in greatly enhanced expression of active WTRXh in transgenic barley seed Analysis by western blot of soluble protein fractions of the three lines in which the thioredoxin gene was linked to a signal sequence (GPdBhssBarWtrx-22, GPdBhssBarWtrx-29 and GPdBhssBarWtrx-7) showed differences in the level of expression (shown in Table 3) Line GPdBhssBarWtrx-22, GPdBhssBarWtrx-29 and GPdBhssBarWtrx-7, respectively, showed 22 times, 10 times and 5 5 times more WTRXh protein than nontransformed control seeds The analyses showed that the thioredoxin content of the null segregant (GPdBhssBarWtrx-29-11 ) was approximately half that of the corresponding control The three lines generated from the construct in which the thioredoxin gene was not associated with a signal sequence were also compared to nontransformed control barley seed and they exhibited the following increases in TRXh levels as indicated by the western blot analyses GPDhBarWtrx-9 12 times, GPDhBarWtrx-5 6 3 times, GPdBhBarWtrx-2 6 4 times When probed on Western Blots, the transgenic lines show two bands while the control barley generaly shows only one and in some cases a second minor band Furthermore, the tissues from the transgenic lines were characterized by a band that did not correspond to either of the barley bands but did correspond to wheat thioredoxin h These data indicate that the protein introduced by transformation is wheat thioredoxin h Table 3 Western Blot Analyses of Overexpression of Wheat Thioredoxin /? in Barley The Wheat thioredoxin h in Barley Grains is Biologically Active Because of interference from other enzymes that oxidize NADPH, the activity of TRXh cannot be accurately assayed in crude extracts, thereby necessitating its partial purification Partially purified extracts of the different transgenic and control lines were prepared from 15 grams of seed using ammonium sulfate fractionation and gel filtration chromatography Activity was measured with an NADP-MDH activation assay Profiles based on these assays show that the activity of TRXh in the transformed seed is much higher than in the nontransformed control (see Figure 7) The activity results are summarized in Table 4 Total WTRXh activity from the seeds of two lines transformed with the B1 -hordein promoter and the signal sequence (GPBhssBarWtrx-3, GPdBhssBarWtrx-29) is about 4- to 10- fold higher, respectively, than that of control, nontransformed seed Total activity from a line transformed with the D-hordein promoter without the signal sequence (BGPDhBbarWtrx-5) is only slightly higher (1 25-fold) than that of the nontransformed control (see Table 4) In the transgenics, the specific activity of thioredoxin is generally about 0 128 protein or about two fold over null segregants Table 4 Summary of Total Bufrer-Extracted Protein and Total Thioredoxin Activity from Active Fraction after Gel Filtration 'Numbers in brackets are fold increase over that of the control The transformed barley grains analyzed so far appear to have more total buffer-extracted protein than control, nontransformed seed (Table 4) The transformed grains have a thioredoxin content of at least about 10-15 μg thioredoxm/mg soluble proteιn(about 2-8 μg thioredoxm/mg tissue) or about two-fold higher than the null segregant Because of the tediousness of the (NH 4 ) 2 S0 4 procedure and the requirement for large quantities of seed, the original extraction procedure was modified to include a heat treatment step This change was based on the fact that £ coli WTRXh is stable after treatment at 60°C for 10 mm (Mark and Richardson, 1976) Results on WTRX from two different transgenic barley seeds (GPdBhBarWtrx-3, GPdBhssBarWtr-29) showed no significant difference in activity between the heat treated and non-heat treated extracts (Figure 8) in addition heat-treatment decreased the endogenous, nonspecific activity in this assay, thereby increasing the reliability of the measurements Ten different barley lines (transformed and nontransformed) were extracted using the heat-treatment step and assayed with the NADP-MDH assay, the results are summarized in Table 5 in general, total WTRXh activities in seeds from lines transformed with the B-hordem promoter and signal sequence linked to wtrxh are much higher (4- to 35-fold) than in seeds from lines transformed with the same promoter without signal sequence linked to wtrxh or in seeds from the nontransformed control (Table 5) At this point it is not known whether all expressed wheat WTRXh in barley seeds is heaj: stable Table 5 Relative Total Thioredoxin Activity in Different Transgenic Barley Lines One hundred percent of (a) total protein, mg, (b) total activity, nmol/min, and (c) specific activity, nmol/min/mg protein of the non-transgenic control are (a) 116 4, (b) 157 38 (c) 1 52, respectively Of the stably transformed lines that expressed wheat thioredoxin /?, on average, its level was found to be higher in transformants that had the signal peptide-containmg constructs than to those that did not (Table 5) Western blot analysis of soluble protein fractions from heterozygous mixtures of seeds from three of the lines, GPdBhssBarWtrx-7, GPdBhssBarWtrx-29, and GPdBhssBarWtrx-22 showed 5 5 times, 22 times, and 10 times more thioredoxin /?, respectively, than nontransformed control gram (Table 3) The thioredoxin content of the null segregant (GPdBhssBarWtrx-29-11-10) was about half that of the corresponding, nontransformed control Extracts from barley typically showed one immunologically reactive band (identified by B in Figure 9A, lanes 1 and 6) but in some transfers showed a second faint, faster moving band (Figure 9B, lane 2) Tissues from transgenic lines overexpressmg wtrxh were characterized by a band that did not correspond to either of the two counterparts in barley, but rather to thioredoxin h from wheat The difference between the overexpressed 13 5-kDa wheat and the endogenous 13 1-kDa barley " thioredoxin /? is particularly pronounced in the barley line transformed with the nontargeted thioredoxin h gene (Figure 9A, line 5 and Figure 9B, lane 1 ) Repeated analyses of the various transgenic lines by SDS/PAGE led to the conclusion that the band identified in Figures 9A-B by W corresponds to the bread wheat wtrxh introduced by barley Independent biochemical assays with 5,5'-dιthιobιs(2- nitrobenzoic acid) (DTNB) (Fiorencio ef al , 1988 ) confirmed the ability of barley NTR to reduce wheat thioredoxin h (data not shown) Because of their value in assessing biochemical attributes of the gram, homozygous wtrxh lines were identified and analyzed by Western blot The two lines identified as homozygous showed both enhanced expression of thioredoxin h relative to that of their heterozygous parents and nontransformed controls Analysis of GPdBhssBarWtrx-29-3 is shown in Figure 10 It is noted that demonstration of the thioredoxin ? present in the nontransgenic control and null segregant grains (not apparent in the exposure shown in Figure 9) required conditions that led to overexposure of the enriched transgenic preparations Thioredoxin in the parent heterozygous gram was shown to be biochemically active Pullulanase and Pullulanase Inhibitor Activity in Baήey Gram Overexpressmg Thioredoxin h Pullulanase is an amylolytic enzyme present in cereal grain, which has a disulfide inhibitor protein (Macn et al , 1993 , MacGregor et al , 1994 ), the activity of which is linked to thioredoxin (Wong ef al , 1995 ) Thioredoxin reduced by NADPH via NTR, reduces the disulfide bonds of the inhibitor, allowing the targeted pullulanase enzyme to be active Because of this relationship, it was of interest to determine the activity of pullulanase in the thioredoxin /7-overexpressιng transformants Spectrophotometπc assays (Figure 13A) of extracts from transformed gram of a homozygous line (GPdBhssBarWtrx-29-3) overexpressmg thioredoxin /? showed a 3- to 4-fold increase in pullulanase activity on the fifth day after initiation of germination relative to its null segregant Confirmatory results were obtained in a separate experiment with native activity gels The increase in activity was apparent either when gels were viewed directly (Figure 13B) or when the activity on the gels was assessed by scanning and integrating the clarified bands (Figure 13C) A homozygous line isolated from a different, independent transformation event (GPdBssBarWtrx-2-1-15) showed a similar response (data not shown) The transgenic plants expressed an pullulanase activity of about 1-2 Absorbance units at 534 nm/30 mm/mg protein, which is about two-fold higher than null segregants Pullulanase inhibitor activity was determined on fractions heated to inactivate pullulanase (70°C for 15 mm) by measuring the inhibition of the fractions on added purified barley malt pullulanase The endogenous pullulanase activity was shown to be completely eliminated by this heat treatment whereas inhibitor activity was not affected (Macn ef al , supra, MacGregor ef al , supra) Analysis of comparable grain extracts revealed that the pullulanase inhibitor was inactive on the fourth and fifth days after water addition in both the transformant and null segregants These results thus demonstrate that the increase in pullulanase activity observed after the third day is not caused by enhanced inactivation of the inhibitor in the transgenic gram It is possible that thioredoxin acts either by increasing the de novo synthesis of pullulanase (Hardie ef al , 1975 ) or by lowering the binding of the mature enzyme to the starchy endosperm There is evidence that some of the pullulanase of the mature endosperm is present in bound form and can be solubilized by reducing conditions (Sissons ef al , 1993 , Sissons et al , 1994 ) Alpha-Amylase Activity m Barley Gram Overexpressmg Thioredoxin h Alpha-amylase, also an amylolytic enzyme that is induced by gibberellic acid like pullulanase, has long been considered key to germination The synthesis of the major (B) and minor (A) forms of this enzyme are known to be triggered by the hormone, gibberellic acid (GA) In addition, alpha-amylase activity is increased in vitro by the reductive inactivation of its disulfide inhibitor protein by thjoredoxin /? (in the presence of NADPH and NADP-thioredoxin reductase) The present results with transformed barley seeds show that, like pullulanase, thioredoxin h expression alters alpha-amylase activity In this case, the appearance of the enzyme during germination is accelerated and its abundance and activity are increased Figure 14A-D shows the early increase in both the abundance and activity of alpha-amylase (A + B forms) during gemination and seedling development Based on the antibody response in western blots, alpha-amylase was first detected 3 days after the onset of germination in the transgenic grain Figure 14C) whereas the enzyme did not appear until the fourth day in the null segregant (Figure 14A) The onset of activity (based on the activity gel) followed a similar pattern (Figure 14B and Figure 14D) The mobility of the enzyme in the activity gel also reflected the early induction of activity in the transgenic grain (Figure 15) That much of this increase in activity seen early on was due to the-B (a gibberellic acid-linked form) is supported by Figure 16 Here, one can also see that the level of the minor A form of the enzyme (also gibberellic acid dependent) was increased in gram overexpressmg thioredoxin /? Again, the appearance of significant levels of the major (B form) alpha-amylase enzyme was advanced by 1 day Germination of Barley Grains Overexpressmg Thioredoxin h All operations were carried out at 25°C (unless otherwise specified below) under conditions described by Kobrehei ef al 1992 and Lozano ef al 1996 Grains were surface sterilized by continuous stirring in 0 25% bleach for 30 mm Bleach was removed by extensive washing with sterilized distilled water Thirty sterilized null segregant (GPdBhssBarWtrx-29-22-10, in which the transgene was removed by crossing with a self-polmated plant from the same line) and thirty sterilized homozygous (GPdBhssBarWtrx-29-3) seeds were placed in each of a series of plastic Petπ dishes (12 5 cm diameter) fitted with three layers of Whatman #1 filter paper moistened with 15 ml sterile distilled water Plates were wrapped with aluminum foil and gram was germinated in a dark chamber at 20°C for up to 7 days One plate was read at each time point shown in Figure 17 Percent germination, in the first day (from the start of incubation up to 24 hours), was determined by observing the emergence of the radicle On the subsequent days, percent germination represents seedling growth as determined by measuring the length of coleoptile and roots of the germinated grains The results, shown in Figure 17, indicate that germination in transgenic barley overexpressmg wheat thioredoxin /? is detected about 16 hours after the onset of incubation in about 25-30% of the seeds In contrast, no germination in the null segregant was detected at 16 hours but is first detected 8 hours later, on Day 1 Therefore, in the transgenic germination is advanced about 8 hours However, on Day 1 germination was detected in approximately 70% or about twice the number of transgenic grains in comparison to their null segregant counterparts It is interesting to note that the onset of germination in the transgenics parallels the onset of the detection of alpha amylase as shown in Figure 15 Seguential Extraction of Gra Proteins from Transgenic Barley Grains Isolated endosperm from 10 dry grains or seedlings (germinated as described above) were ground with mortar and pestle at 4°C with 3 ml Tπs-HCI buffer as indicated below The separate mixtures of homozygous GPdBhssBarWtrx-29-3 and null segregant GPdBhssBarWtrx-29-22-10 grains were placed in a 5-ml screw-top centrifuge tube Grains were mechanically shaken for 30 minutes and then centrifuged for 10 m at 24,000 x g The supernatant fraction (buffer-soluble) was decanted and saved for analysis and the residue was extracted sequentially with the following solvents for the indicated times [1] 0 5 M NaCl (30 mm), [2] water (30 m ), [3] 2 x 50% propanol (2 hr), [4] 2 x 50% propanol + 2% 2-mercaptoethanol (MET) (2 hr), and [5] 0 5 M borate buffer, pH 10, containing 1% SDS and 2% 2-mercaptoethanol (2 hr) Supernatant fractions of all extracts were determined for volume and protein content (by Coomassie dye binding method), then were stored at -20°C until use By convention, the fractions are designated [1] albumin/globulin (buffer/salt/water), [2] Hordein I (propanol), [3] Hordein II (propanol + MET), and [4] glutelm (Borate/SDS/MET) (Shewry et al , 1980) These fractions were used to determine, protein content, the distribution of proteins between the water soluble -and insoluble fractions, the total extractable protein, and reduction with NADPH To determine the in vivo redox status of protein from transgenic barley grain during germination and seedling development, the extraction procedure was repeated except that 2 mM mBBr was included in the Tπs grinding buffer and the grinding was under liquid nitrogen The mBBr denvatized proteins were electrophoresed on SDS-poiyacrylamide gels (1 5 mm thickness, 10 - 20% gels, pH 8 5 (Laemmli, 1970) Gels were developed for 16 hr at a constant current of 8 mA Following electrophoresis, gels were placed in 12% (w/v) trichloroacetic acid and soaked for 4 to 6 hr with one change of solution to fix the proteins, gels were then transferred to a solution of 40% methanol/10% acetic acid for 8 to 10 hr with agitation to remove residual mBBr The fluorescence of mBBr (both free and protein bound mBBr), was visualized by placing gels on a light box fitted with an ultraviolet light source (365 nm) Following removal of the excess (free) mBBr, images of gels were captured by Gel Doc 1000 (Bio-Rad) To ascertain the equivalent protein amount of loaded extracts, SDS-gels were stained with Coomassie Brilliant Blue G-250 in 10% acetic acid for 30 mm, and destamed in 10% acetic acid for 30 mm with the aid of a microwave oven Protein stained gels were captured by Gel Doc 1000 as above The quantification of fluorescence (pixel x mm x mm) and protein (optical density x mm x mm) on gels were carried out by a software program for image analysis - Multi-Analyst, version 1 0 (Bio-Rad) Relative reduction was expressed as the ratio of fluorescence to protein The results of two experiments shown in Table 6, Table 7, and Table 8 demonstrate an increase in the total protein on a percent grain and a percent weight basis in the transgenic barley as compared to the null segregant The transgenic have a thioredoxin content that is at least two-fold higher (10-15 μg/mg soluble protein, 2-8μg/gram tissue) than the null segregant The data indicate that this increase in total extractable protein is the result in redistribution of the protein to the most soluble albumin/globulin fraction The redistribution of the protein to the soluble fraction increase in the transgenics is at least 5% higher than the controls Table 6 Protein Content of Various Fractions in Transgenic Barley Gram Overexpressmg Wheat Thioredoxin h "Weight per 10 seeds is 0 377 and 0 402 full null segregant and homozygous line of transgenic barley Table 7 Protein Content of Various Fractions in Transgenic Barley Gram Overexpressmg Wheat Thioredoxin /? *Weιght per 10 seeds is 0 377 and 0 402 for null segregant and homozygous line of transgenic barley Table 8 Percent Increase of Extractable Protein in Homozygous Line Analysis of the relative redox status (SH SS) of protein fractions in transgenic and null segregant barley grains during germination and as dry grains are shown in Figure 18 In dry transgenic gram, the greatest increase in reduction relative to the null segregant was observed in the hordein I fraction This increase was paralleled by decreases in the relative redox status in the hordein II and glutelm fractions while the relative redox status of the albumin/globulin fraction was unchanged The relative redox status of the transgenic in comparison to the null segregant is at least 5 1 Duπng germination, the albumin/globulin fraction progressively increases, reaching a relative redox ratio of about 1 5 on Day 4 The relative redox status of the hordein II and glutelm fractions also increased during germination but only reached parity with the null segregant In contrast the relative redox status of the hordein I fraction was highly variable Example 4 Barley Thioredoxin h Gene (btrxh) Transformation Materials and Methods Plant Matenal and Culture of Explants Mature seeds of rice (Oryza sativa L cv Taipei 309) were surface-sfeπlized for 20 m in 20%(v/v) bleach (525% sodium hypochlonte) followed by 3 washes in sterile water The seeds were placed on 2 different NB (Chen L et al (1998) Plant Cell Rep 18 25-31)-based callus-induction media, (1) NBD'BC2 medium containing 2 0 mg/L 2,4-D, 0 1 mg/L BAP and 0 5 μM CuS0 4 (Cho M -J , unpublished), (2) NBDBC3 medium containing 1 0 mg/L 2,4-D, 0 5 mg/L BAP and 5 0 μM CuS0 4 (Cho M -J , unpublished) Five to 7 d after plating, germinating shoots and roots from the mature seeds were completely removed by manual excision After three weeks of incubation at 24+1 °C under dim-light conditions (approximately 10 to 30 μEm 2 s 1 , 16 h-light), tissues with shiny, nodular and compact structures were selected and subsequently maintained on NBDBC4 medium containing 0 5 mg/L 2,4-D, 2 0 mg/L BAP and 5 0 μM CuS0 4 (Cho M -J , unpublished), subcultuπng at 3 to 4 week intervals, to proliferate highly regenerative, green tissues Construction of a Barley Thioredoxin h Expression Vector and DNA Seguencmg pdBhssBTRXN(Km)-2 (Cho M -J , unpublished) the chimeric DNA construct containing the B r hordeιn promoter-signal sequence-J frx/? (barley thioredoxin h gene) was obtained using a modified method of site-directed mutagenesis by PCR (Cho and Lemaux 1997) The four-primer strategy was used to produce 2 major PCR products Primers, Bhor7 (5'-GTAAAGCTTrAACA4CCCAC4CATTG-3', SEQ ID NO 41) containing H/ndlll restriction site and BhorssBtrx2R (5'-CGCCGTTGCCGACGCCGCTGCAATCGTACTTGTTGCCGCAAT-3', SEQ ID NO 42), were used for amplification of 0 49-kb B hordeιn 5' region including the B r hordeιn signal peptide sequence using the λ2-4/H/πdlll plasmid containing genomic clone of B.-hordem (Brandt ef al , 1985, Cho ef al , 1997) as a template The primer BhorssBtrx2R is an overlapping primer containing the btrxh coding sequence (italicized) and a partial signal peptide sequence from the B, -hordein promoter without the ATG initiation codon for btrxh The second PCR product was amplified using primers, BorssBtrx4 (5'-ACAAGTACGATTGCAGCGGCGrCGGCAACGGC-3', SEQ ID NO 43) and Btrxh2R (atagagctcTTACTGGGCCGCCGCGTG, SEQ ID NO 44), cDNA clone containing btrxh (Caillau, del Val, Cho, Lemaux and Buchanan, unpublished) was used as template The second set of PCR reactions was produced 0 86-kb chimeric fragments using two PCR-amplified fragments (each diluted 50 times) and two external primers, Bhor7 and Btrx2R pdBhssBTRXN(Km)-2 was made by replacing the maize ubiqutm promoter in pUbιlNosKmf(-) with the 0 86-kb PCR-amplified Hιnd\\\ISac\ fragment containing B -hordem promoter with its signal peptide sequence plus btrxh Thus, construct pdBhssBTRXN(Km)-2 contains the barley endosperm-specific B,-hordeιn promoter with its signal peptide sequence, btrxh and nos The signal peptide sequence containing the ATG initiation codon was directly combined with the sequence of the btrxh gene, without having extra ammo acid sequences between the two, in order to make barley thioredoxin ? protein provide a precise cleavage site in the lumen of endoplasmic reticulum (ER) The PCR-amplified region of the construct was further confirmed by DNA sequencing, and used for stable transformation of rice Stable Transformation Approximately 4- to 5-month-old highly regenerative cultures maintained on NBDBC4 medium were used for bombardment Tissue pieces (3-4 mm) were transferred for osmotic pretreatment to NBDBC4 medium containing mannitol and sorbitol (0 2 M each) Four hours after treatment with osmoticum, tissues were bombarded as previously described (Lemaux et al 1996, Cho et al 1998) Gold particles (1 0 μm), coated with 25 μg of a mixture of pActl IHPT-4 and pdBhssBTRXN(Km)-2 at a molar ratio of 1 2 were used for bombardment with a Bio-Rad PDS- 1000 He biolistic device (Bio-Rad, Hercules, CA) at 900 or 1100 psi. Sixteen to 18 h after bombardment, tissues were placed on osmoticum-free NBDBC4 medium supplemented with 20 mg/L hygromycin B and grown at 24±1°C under dim-light (10-30 μEnτ 2 s "1 ) From the third round of selection onward, tissues were subcultured at 3- to 4-week intervals on NBDBC4 medium containing 30 mg/L hygromycin B When a sufficient amount (a plate) of the putatively transformed highly regenerative tissue was obtained, it was plated on NBNBC4 medium containing 0 5 mg/L NAA, 2 0 mg/L BAP and 5 0 μM CuS0 4 (Cho M -J , unpublished) and exposed to higher intensity light (approximately 45-55 μEm 1 ) Green shoots were then transferred to Magenta boxes containing phytohormone-free regeneration medium [MS (Murashige and Skoog (1962) Physiol Plant 15473-497) plus 20 g/L sucrose] with 10 to 20 mg/L hygromycin B After four weeks, regenerated plantlets were transferred to soil Genomic DNA Isolation. Polymerase Cham Reaction (PCR) Putative transgenic lines were screened by DNA PCR using two a set of btrxh primers, Btrxhδ (5'- CCAAGAAGTTCCCAAATGC-3', SEQ ID NO 45) and Btrxh2R PCR amplification resulted in 0 19-kb intact btrxh from transgenic lines One fafrx/?-posιtιve line (OSHptBTRX-l) was obtained Amplifications were performed in a 25-μl reaction with Taq DNA polymerase (Promega, Madison, Wl) as described (Cho ef al 1998) Example 5 Barley NTR Gene (bntr) Transformation NADP/thioredoxin system (NTS), is analogous to the system established for animals and most microorganisms, in which thioredoxin (/?-type in plants) is reduced by NADPH and NADP-thioredoxin reductase (NTR) (Johnson et al , 1987a, Fiorencio et al , 1988, Suske ef al , 1979) Without being bound by theory, the NTR appears to be a limiting factor for NTS Therefore, we isolated barley ntr gene from barley cDNA library (Cho, Lemaux and Buchanan unpublished) and introduce this gene into barley, wheat, and rice plants Construction of a Barley NTR Expression Vector and DNA Seguencmg pActιlBNTRN-4 (Cho M -J , unpublished) pActιlBNTRN-4 was made by ligat g the PCR-amplified Xbal/Kpn\ fragment containing barley nfrcDNA sequence Primers, BNTR29 (5'attctaαaATGGAGGGATCCGCCGCGGCGCCGCTC-3'. SEQ ID NO 46) and BNTR23R (5'- ttqqtaccTCAATCAGACTTGCCCACCTGT-3', SEQ ID NO 47), were used for amplification of the 1 012-Kb Xba\IKpn\ fragment containing 0 996-Kb barley ntr coding sequence, small letters contain a restriction enzyme site for subcloning of the DNA construct containing barley ntr gene and underlined letters indicate the barley ntr sequences 1 he barley ntr fragment was purified from a 0 7% agarose gel using QIAquick® gel extraction kit, digested with Xbal and Kpn\ and ligated into Xibal/Kpπl-digested pActl INosKmf(-) to generate the pActιlBNTRN-4 plasmid Nucleotide sequences of the PCR-amplified barley ntr coding region were determined by DNA sequencing Barley ntr expression vectors driven by barley endosperm-specific B r or D-hordein promoter with or without its signal peptide sequence are constructed Stable transformation Transformation of barley, wheat and rice is conducted as previously described above and in Lemaux et al , 1996, Cho et al , 1998, Kim et al , 1999 Barley trxh alone, barley ntr alone or a mixture of both genes are used for bombardment with a Bio-Rad PDS-1000 He biolistic device (BioRad, Hercules, CA) at 900 or 1100 psi After obtaining transgenic lines, they arel analyzed for tests of redox state, germmability, allergenicity, and baking quality According to the above examples, other types of plants, are transformed in a similar manner to produce transgenic plants overexpressmg thioredoxin and NTR either alone or in combination, such as transgenic wheat, rice, maize, oat, rye sorghum, millet, tπticale, forage grass, turf grass, soybeans, lima beans, tomato, potato, soybean, cotton, tobacco etc Further, it is understood that thioredoxins other than wheat or barly thioredoxin or thioredoxin h can be used in the context of the invention Such examples include spinach ?, chloroplast thioredoxin m and f, bacterial thioredoxins (e g , E coli ) yeast, and animal and the like In addition, it is understood the NTR other than barley NTR protein also can be used in the context of the invention such as spinach, wheat, and NTR of monocots and dicots This invention has been detailed both by example and by description It should be apparent that one having ordinary skill in the relevant art would be able to surmise equivalents to the invention as described in the claims which follow but which would be within the spirit of the foregoing description Those equivalents are included within the scope of this invention All herein cited patents, patent applications, publications, references and references cited therein are hereby expressly incorporated by reference in their entirety REFERENCES Ainley WM, McNeil KJ, Hill JW, Lmgle WL, Simpson RB, Brenner ML, Nagao RT, Key JL (1993) Regulatable endogenous production of cytokmins up to "toxic" levels in transgenic plants and plant tissues Plant Molecular Biology 22(1) 13-23 Altschul ef al (1990) J Mol Biol , 215 403-10 Altschul ef al (1994) Nature Genet , 6 119-29 Altschul et al , 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entirety

Claims: We claim 1 A recombinant nucleic acid encoding a thioredoxin ? protein comprising a nucleic acid that hybridizes under high stringency conditions to a sequence complementary to that set forth in Figure 2 (SEQ ID NO 1) 2 The recombinant nucleic acid of claim 1 comprising a nucleic acid sequence as set forth in Figure 2 (SEQ ID NO 1 ) 3 A recombinant nucleic acid encoding a thioredoxin h protein comprising a nucleic acid having at least 75% sequence identity to a sequence as set forth Figure 2 (SEQ ID NO 1 ) 4 A recombinant nucleic acid encoding an ammo acid sequence as shown in Figure 1 (SEQ ID NO 2) 5 A host cell comprising the recombinant nucleic acid of claim 1 , 2, 3, or 4 6 An expression vector comprising the recombinant nucleic acid of claim 1 , 2, 3, or 4 operably linked to a transcriptional regulatory sequence 7 A host cell comprising an expression vector comprising the recombinant nucleic acid of claim 1 , 2, 3, or 4 operably linked to a transcriptional regulatory sequence active said host cell 8 A transgenic plant comprising the recombinant nucleic acid of claim 1 , 2, 3, or 4 9 A transgenic plant comprising an expression vector comprising the recombinant nucleic acid of claim 1, 2, 3, or 4 operably linked to transcriptional regulatory sequences active in said plant 10 A transgenic plant comprising a host cell comprising an expression vector comprising the recombinant nucleic acid of claim 1 , 2, 3, or 4 operably linked to a transcriptional regulatory sequence active in said cell 11 The transgenic plant of claim 10 wherein said host cell is a seed cell 12 A transgenic seed comprising the recombinant nucleic acid of claim 1 , 2, 3, or 4 operably linked to transcriptional regulatory sequences active in said seed 13 A method of expressing a thioredoxin /? protein comprising cultuπng a host cell comprising the recombinant nucleic acid of claim 1 under conditions suitable for expression of said thioredoxin /? protein A method of expressing a thioredoxin h protein comprising cultuπng a host cell comprising an expression vector comprising the recombinant nucleic acid of claim 1 operably linked to regulatory sequences active in said host cell under conditions suitable for expression of said thioredoxin /? protein A method of expressing a thioredoxin /? protein comprising cultuπng a transgenic plant comprising the recombinant nucleic acid of claim 1 under conditions suitable for expression of said thioredoxin h protein A method of expressing a thioredoxin /? protein comprising cultuπng a transgenic plant comprising an expression vector comprising the recombinant nucleic acid of claim 1 operably linked to regulatory sequences active in said transgenic plant under conditions suitable for expression of said thioredoxin /? protein A method of expressing a thioredoxin h protein comprising cultuπng the transgenic seed of claim 12 The method of claim 13, 14, 15, 16, or 17 further comprising recovering said protein A recombinant thioredoxin h polypeptide encoded by the recombinant nucleic acid of claim 1 A recombinant thioredoxin /? polypeptide comprising an ammo acid sequence having at least 80% sequence identity with the sequence set forth in Figure 15 (SEQ ID NO 25) The recombinant thioredoxin h polypeptide of claim 20 wherein said sequence is set forth in Figure 15 (SEQ ID NO 25) An antibody that specifically binds to the recombinant polypeptide of claim 19 The antibody of claim 22 wherein said antibody is a monoclonal antibody The antibody of claim 22 wherein said antibody inhibits a biochemical property of a recombinant thioredoxin /? polypeptide comprising an am o acid sequence having at least 80% sequence identity with the sequence set forth in Figure 1 (SEQ ID NO 2) A method of identifying a bioactive agent that binds to a thioredoxin h polypeptide comprising an ammo acid sequence having at least 80% sequence identity with the sequence set forth in Figure 1 (SEQ ID NO 2), said method comprising a) combining said thioredoxin h polypeptide and a candidate bioactive agent, and b) determining the binding of said candidate bioactive agent to said thioredoxin h βolypeptide, whereby said bioactive agent is identified A method of identifying a bioactive agent that modulates an activity of a thioredoxin /? polypeptide comprising an ammo acid sequence having at least 80% sequence identity with the sequence set forth in Figure 1 (SEQ ID NO 2), said method comprising, a) combining said thioredoxin h polypeptide and a candidate bioactive agent(s), and b) determining the effect of said candidate bioactive agent(s) on an activity of said thioredoxin /? polypeptide The method of claim 25 or 26, wherein step a) is combining said thioredoxin h polypeptide and a library of candidate bioactive agents The method of claim 25 or 26 further comprising identifying said bioactive agent A recombinant nucleic acid encoding an NTR protein comprising a nucleic acid that hybridizes under high stringency conditions to a sequence complementary to that set forth in Figure 5A (SEQ ID NO 10) The recombinant nucleic acid of claim 29 comprising a nucleic acid sequence as set forth in Figure 5A (SEQ ID NO 10) A recombinant nucleic acid encoding an NTR protein comprising a nucleic acid having at least 75% sequence identity to a sequence as set forth in Figure 5A (SEQ ID NO 10) A recombinant nucleic acid encoding an am o acid sequence as shown in Figure 4 (SEQ ID NO 9) A host cell comprising the recombinant nucleic acid of claim 29, 30, 31 , or 32 An expression vector comprising the recombinant nucleic acid of claim 29, 30, 31 , or 32 operably linked to a transcriptional regulatory sequence A host cell comprising an expression vector comprising the recombinant nucleic acid of claim 29, 30, 31 , or 32 operably linked to a transcriptional regulatory sequence active said host cell A transgenic plant comprising the recombinant nucleic acid of claim 29, 30, 31 , or 32 A transgenic plant comprising an expression vector comprising the recombinant nucleic acid of claim 29, 30, 31 , or 32 operably linked to transcriptional regulatory sequences active in said plant A transgenic plant comprising a host cell comprising an expression vector comprising the recombinant nucleic acid of claim 29, 30, 31 , or 32 operably linked to a transcriptional regulatory sequence active in said cell The transgenic plant of claim 38 wherein said host cell is a seed cell A transgenic seed comprising the recombinant nucleic acid of claim 29, 30, 31 , or 32 operably linked to transcriptional regulatory sequences active in said seed A method of expressing an NTR protein comprising cultuπng a host cell comprising the recombinant nucleic acid of claim 29 under conditions suitable for expression of said NTR protein A method of expressing an NTR protein comprising cultuπng a host cell comprising an expression vector comprising the recombinant nucleic acid dϊ claim 29 operably linked to regulatory sequences active in said host cell under conditions suitable for expression of said NTR protein A method of expressing an NTR protein comprising cultuπng a transgenic plant comprising the recombinant nucleic acid of claim 29 under conditions suitable for expression of said NTR protein A method of expressing an NTR protein comprising cultuπng a transgenic plant comprising an expression vector comprising the recombinant nucleic acid of claim 29 operably linked to regulatory sequences active in said transgenic plant under conditions suitable for expression of said NTR protein A method of expressing an NTR protein comprising cultuπng the transgenic seed of claim 40 The method of claim 41 , 42, 43, 44, or 45 further comprising recovering said protein A recombinant NTR polypeptide encoded by the recombinant nucleic acid of claim 29- A recombinant NTR polypeptide comprising an ammo acid sequence having at least 80% sequence identity with the sequence set forth in Figure 4 (SEQ ID NO 9) The recombinant NTR polypeptide of claim 48 wherein said sequence is set forth in Figure 4 (SEQ ID NO 9) An antibody that specifically binds to the recombinant polypeptide of claim 47 The antibody of claim 50 wherein said antibody is a monoclonal antibody The antibody of claim 50 wherein said antibody inhibits a biochemical property of a recombinant NTR polypeptide comprising an ammo acid sequence having at least 80% sequence identity with the sequence set forth in Figure 4 (SEQ ID NO 9) A method of identifying a bioactive agent that binds to an NTR polypeptide comprising an ammo acid sequence having at least 80% sequence identity with the sequence set forth in Figure 4 (SEQ ID NO 9), said method comprising a) combining said NTR polypeptide and a candidate bioactive agent, and b) determining the binding of said candidate bioactive agent to said NTR polypeptide, whereby said bioactive agent is identified A method of identifying a bioactive agent that modulates an activity of an NTR polypeptide comprising an ammo acid sequence having at least 80% sequence identity with the sequence set forth in Figure 4 (SEQ ID NO 9), said method comprising, a) combining said NTR polypeptide and a candidate bioactive agent(s), and b) determining the effect of said candidate bioactive agent(s) on an activity of said NTR polypeptide The method of claim 53 or 54, wherein step a) is combining said NTR polypeptide and a library of candidate bioactive agents The method of claim 52 or 53 further comprising identifying said bioactive agent The transgenic plant of claim 9, wherein said recombinant nucleic acid is overexpressed in said transgenic plant in comparison to a non-transgenic plant of the same species The transgenic plant of claim 37, wherein said recombinant nucleic acid is overexpressed in said transgenic plant in comparison to a non-transgenic plant of the same species An isolated nucleic acid encoding a thioredoxin /? protein comprising a nucleic acid that hybridizes under high stringency conditions to a sequence complementary to that set forth in Figure 2 (SEQ ID NO 1) The isolated nucleic acid of claim 59 comprising a nucleic acid sequence as set forth in Figure 2 (SEQ ID NO 1) An isolated nucleic acid encoding a thioredoxin /? protein comprising a nucleic acid having at least 75% sequence identity to a sequence as set forth in Figure 2 (SEQ ID NO 1) An isolated nucleic acid encoding an ammo acid sequence as shown in Figure 1 (SEQ ID NO 2) 63 A transgenic plant comprising the isolated nucleic acid of claim 59, 60, 61 , or 62 64 A transgenic seed comprising the isolated nucleic acid of claim 59, 60, 61 , or 62 operably linked to transcriptional regulatory sequences active in said seed 65 A isolated nucleic acid encoding an NTR protein comprising a nucleic acid that hybridizes under high stringency conditions to a sequence complementary to that set forth in Figure 5A (SEQ ID NOJ0). 66. The isolated nucleic acid of claim 65 comprising a nucleic acid sequence as set forth in Figure 5A (SEQ ID NO: 10) 67 An isolated nucleic acid encoding an NTR protein comprising a nucleic acid having at least 75% sequence identity to a sequence as set forth in Figure 5A (SEQ ID NO.10) 68 An isolated nucleic acid encoding an ammo acid sequence as shown in Figure 4 (SEQ ID NO:9) 69 A transgenic plant comprising the isolated nucleic acid of claim 65, 66, 67, 68, or 69. 70 A transgenic seed comprising the recombinant nucleic acid of claim 65, 66, 67, 68, or 69. operably linked to transcriptional regulatory sequences active in said seed 71 A transgenic plant or at least a part of said plant overexpressmg a barley thioredoxin h protein 72 A transgenic plant or at least a part of said plant overexpressmg a barley NADP-thioredoxin reductase protein

Inventors: BUCHANAN BOB B, CAILLAU MAXIME, CHO MYEONG-JE, DEL VAL GREG, LEMAUX PEGGY G, BUCHANAN, BOB, B., CAILLAU, MAXIME, CHO, MYEONG-JE, DEL VAL, GREG, LEMAUX, PEGGY, G.
Applicants: BUCHANAN BOB B, CAILLAU MAXIME, CHO MYEONG JE, DEL VAL GREG, LEMAUX PEGGY G, UNIV CALIFORNIA, BUCHANAN, BOB, B., CAILLAU, MAXIME, CHO, MYEONG-JE, DEL VAL, GREG, LEMAUX, PEGGY, G., THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
Application year: 2000
Main classification: C07K14
IPC codes: A01H5, A21D13, A23J1, A23L1, C07K14, C07K16, C12N1, C12N5, C12N9, C12N15, C12P21, C12Q1, G01N33