bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular cloning of the cDNA encoding the Epstein-Barr virus/C3d receptor (complement receptor type 2) of human B lymphocytes.
Authors: Moore M D , Cooper N R , Tack B F , Nemerow G R
Published: May 2006

Complementary DNA clones for complement receptor type 2 (CR2), the B-lymphocyte membrane protein that serves as the receptor for Epstein-Barr virus and the C3d complement fragment, were obtained by screening a lambda gt11 library generated from Raji B lymphoblastoid cell mRNA. A 4.2-kilobase (kb) clone, representing the entire coding sequence of the protein plus untranslated 5' and 3' nucleotide sequences was obtained and sequenced. The 4.2-kb clone, which contains all but about 500 base pairs (bp) of the 5' untranslated region of the full-length CR2 mRNA, consists of 63 bp of 5' untranslated nucleotide sequence followed successively by a start codon, a 20-amino acid hydrophobic signal peptide, 1005 amino acids having a repeating motif, a 28-amino acid probable transmembrane domain, and a 34-amino acid cytoplasmic tail. The deduced amino acid sequence of the protein indicates that the extracellular domain consists entirely of 16 tandemly arranged repeating elements, each 60-75 amino acids in length, which are identified by multiple conserved residues. This repeating motif also occurs in the C3b/C4b receptor, several complement proteins, and a number of noncomplement proteins. In CR2, the 16 repeats occur in four clusters of four repeats each. Approximately 10% of the deduced amino acid sequence, including the amino and carboxyl termini, was confirmed by amino acid sequencing of tryptic peptides derived from purified CR2. The nucleotide and derived amino acid sequence of CR2 and related studies are presented here.
Brain L-glutamate decarboxylase: purification and subunit structure.
Authors: Denner L A , Wei S C , Lin H S , Lin C T , Wu J Y
Published: May 2006

Glutamate decarboxylase (GDCase; L-glutamate-1-carboxy-lyase, EC 4.1.1.15) was purified from whole rat brain approximately equal to 1300-fold to apparent homogeneity with a specific activity of 2.4 units per mg of protein by a combination of column chromatographies on DEAE-cellulose, hydroxylapatite, and gel filtration, and preparative nondenaturing polyacrylamide gel electrophoresis. The purified preparation contained a single protein band that comigrated with GDCase activity in three diverse analyses: nondenaturing regular (5%) and gradient (3.6-25%) polyacrylamide gel electrophoresis and isoelectric focusing at pH 4-7. The native molecular mass was calculated to be 120 +/- 10 kDa from gradient polyacrylamide gel electrophoresis and 110 +/- 10 kDa from gel filtration. Under the treatment with NaDodSO4 and 2-mercaptoethanol, GDCase dissociated into two subunits of 40 +/- 2 and 80 +/- 4 kDa, as estimated from NaDodSO4 gel electrophoresis. However, only a 40-kDa subunit was detected when GDCase was treated with 4 M urea plus NaDodSO4 and 2-mercaptoethanol, suggesting that the 80-kDa subunit is the dimer of the 40-kDa subunit. In immunoblotting, polyclonal antibodies against GDCase reacted with both 40- and 80-kDa subunits, while monoclonal antibody reacted with only 80-kDa subunits. The isoelectric point of the native enzyme was 5.4. The Km for glutamate was 1.59 X 10(-3) M. In addition to L-glutamate, cysteine sulfinic acid was also decarboxylated at approximately equal to 10% of the rate of glutamate. The pH optimum was fairly broad, with a maximum at approximately equal to 7.3. The enzyme was strongly inhibited by carbonyl-trapping agents, sulfhydryl reagents, thiol compounds, and beta-methylene-DL-aspartate.
Imaging of a glioma using peripheral benzodiazepine receptor ligands.
Authors: Starosta-Rubinstein S , Ciliax B J , Penney J B , McKeever P , Young A B
Published: May 2006

Two types of benzodiazepine receptors have been demonstrated in mammalian tissues, one which is localized on neuronal elements in brain and the other, on glial cells and in peripheral tissues such as kidney. In vivo administration of 3H-labeled PK 11195 [1-(2-chlorophenyl-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide] or [3H]flunitrazepam with 5 mg of clonazepam per kg to rats with intracranial C6 gliomas resulted in high levels of tritiated-drug binding to the tumor as shown by quantitative autoradiography. Pharmacological studies indicated that the bound drugs labeled the peripheral benzodiazepine binding site. Binding to the peripheral benzodiazepine site was confirmed primarily to malignant cells with little binding to adjacent normal brain tissue or to necrotic tissue. Tumor cell binding was completely inhibited by preadministration of the peripheral benzodiazepine blocking agent PK 11195 at 5 mg/kg. The centrally selective benzodiazepine ligand clonazepam had no effect on PK 11195 binding to the tumor cells. When binding to other tumor cell lines grown in nude mice and nude athymic rats was evaluated, little or no peripheral benzodiazepine binding was detected on human pheochromocytoma (RN1) and neuroblastoma (SK-N-MC, SK-N-SH) tumor cells, respectively. However, high densities of peripheral benzodiazepine binding sites were observed on tumors derived from a human glioma cell line (ATCC HTB 14, U-87 MG). The presence of high concentrations of specific peripheral benzodiazepine receptors on glial tumors suggests that human primary central nervous system tumors could be imaged and diagnosed using peripheral benzodiazepine ligands labeled with positron- or gamma-emitting isotopes.
On the translocation of proteins across membranes.
Authors: Singer S J , Maher P A , Yaffe M P
Published: May 2006

Many proteins of intracellular organelles are first synthesized in the cytoplasm and are then specifically transferred across the membranes of the organelles. On the assumption that these transfers all occur by the same basic mechanism, we enumerate the rather stringent requirements that the mechanism must satisfy. A unitary molecular mechanism is then proposed that meets these requirements.
Superinduction of the Dictyostelium discoideum cell surface cAMP receptor by pulses of cAMP.
Authors: Chisholm R L , Hopkinson S , Lodish H F
Published: May 2006

Extracellular cAMP plays a crucial role in regulating the developmental program of Dictyostelium discoideum, functioning as a chemotactic agent, as well as a signal that regulates expression of developmentally expressed genes. These activities appear to be mediated by a cell-surface receptor for cAMP. We have studied the regulation of this receptor in cells developed in starved suspension cultures exposed to 50 nM pulses of cAMP every 6 min. cAMP-pulsed cells display roughly 10-fold higher cAMP receptor levels than cells that developed on filters or that were starved in suspension without cAMP pulses. Based on saturation binding analysis, the superinduced binding activity represents an increase in receptor number, while receptor affinity for cAMP is unaffected. Photoaffinity labeling of superinduced cells results in specific labeling of the same molecules that are labeled in starved cells. This increased cAMP binding activity was also detected in membrane preparations from cAMP-pulsed cells. These results provide evidence for an unusual mode of receptor regulation: autogenous induction of the receptor by its ligand.
Production of glycosylated physiologically "normal" human alpha 1-antitrypsin by mouse fibroblasts modified by insertion of a human alpha 1-antitrypsin cDNA using a retroviral vector.
Authors: Garver R I , Chytil A , Karlsson S , Fells G A , Brantly M L , Courtney M , Kantoff P W , Nienhuis A W , Anderson W F , Crystal R G
Published: May 2006

Alpha 1-Antitrypsin (alpha 1AT) deficiency is a hereditary disorder characterized by reduced serum levels of alpha 1AT, resulting in destruction of the lower respiratory tract by neutrophil elastase. As an approach to augment alpha 1AT levels in this disorder with physiologically normal human alpha 1AT, we have integrated a full-length normal human alpha 1AT cDNA into the genome of mouse fibroblasts. To accomplish this, the retroviral vector N2 was modified by inserting the simian virus 40 early promoter followed by the alpha 1AT cDNA. Southern analysis demonstrated that the intact cDNA was present in the genome of selected clones of the transfected murine fibroblasts psi 2 and infected NIH 3T3. The clones produced three mRNA transcripts (5.8, 4.8, and 2.4 kilobases) containing human alpha 1AT sequences, secreted an alpha 1AT molecule recognized by an anti-human alpha 1AT antibody, with the same molecular mass (52 kDa) as normal human alpha 1AT and that complexed with and inhibited human neutrophil elastase. The psi 2 produced alpha 1AT was glycosylated, and when infused intravenously into mice, it had a serum half-life similar to normal alpha 1AT purified from human plasma and markedly longer than that of nonglycosylated human alpha 1AT cDNA-directed yeast-produced alpha 1AT. These studies demonstrate the feasibility of using a retroviral vector to insert the normal human alpha 1AT cDNA into non-alpha 1AT-producing cells, resulting in the synthesis and secretion of physiologically "normal" human alpha 1AT.
Complete correction of the enzymatic defect of type I Gaucher disease fibroblasts by retroviral-mediated gene transfer.
Authors: Sorge J , Kuhl W , West C , Beutler E
Published: May 2006

Glucocerebrosidase cDNA and the neomycin-resistance gene (neo) were cloned into a retrovirus vector. Mouse fibroblasts infected with this vector expressed human glucocerebrosidase, which was readily distinguished from the mouse enzyme using mouse monoclonal anti-glucocerebrosidase antibodies. Cultured fibroblasts and transformed lymphoblasts from patients with type I Gaucher disease were infected with the retrovirus rescued from the mouse fibroblasts by a helper virus. Transformed cells were selected with the antibiotic G418. The enzyme activity of cells infected with virus containing glucocerebrosidase cDNA was restored to normal, while uninfected cells or cells infected with virus containing only the neo gene did not produce glucocerebrosidase.
II-BGlc, a glucose receptor of the bacterial phosphotransferase system: molecular cloning of ptsG and purification of the receptor from an overproducing strain of Escherichia coli.
Authors: Bouma C L , Meadow N D , Stover E W , Roseman S
Published: May 2006

The bacterial phosphoenolpyruvate:glycose phosphotransferase system (PTS) consists of interacting cytoplasmic and membrane proteins that catalyze the phosphorylation and translocation of sugar substrates across the cell membrane. One PTS protein, II-BGlc, is the membrane receptor specific for glucose and methyl D-glucopyranosides; the protein has been purified to homogeneity from Salmonella typhimurium [Erni, B., Trachsel, H., Postma, P. & Rosenbusch, J. (1982) J. Biol. Chem. 257, 13726-13730]. In the present experiments, the Escherichia coli ptsG locus, which encodes II-BGlc, was isolated from a transducing phage library and subcloned into plasmid vectors. The resulting plasmids complement the following phenotypic defects of ptsG mutants: growth on glucose, uptake and phosphorylation of methyl alpha-D-glucoside, and repression of the utilization of non-PTS sugars by methyl alpha-glucoside. The transformed cells overproduce II-BGlc 4- to 10-fold, and a Mr 43,000 polypeptide was synthesized from the plasmids in an in vitro transcription/translation system. The E. coli and S. typhimurium II-BGlc proteins differ in their physical properties, and a modified, three-step purification procedure was developed for isolating the E. coli protein.
Partly native epitopes are already present on early intermediates in the folding of tryptophan synthase.
Authors: Blond S , Goldberg M
Published: May 2006

Two monoclonal antibodies directed against the native beta 2 subunit of Escherichia coli tryptophan synthase [L-serine hydro-lyase (adding indoleglycerol-phosphate), EC 4.2.1.20], one recognizing the C-terminal F1 domain and the other the N-terminal F2 domain, were used to detect immunoreactive intermediates in the folding of the protein. For that purpose, the association of the monoclonal antibodies with either the beta 2 subunit or its isolated domains was studied by using fluorescence energy transfer between tryptophan residues of the antibodies and a dansyl group covalently linked to the antigen. It is shown that the association of both monoclonal antibodies with the antigen occurs within a few seconds after initiation of the renaturation, whereas complete refolding of the beta 2 subunit requires several minutes under the same experimental conditions. Thus, immunoreactive intermediates appear to be formed at an early stage of the folding process. While the isolated F1 domain alone is able to rapidly refold into a conformational intermediate already well recognized by the anti-native-beta 2 antibody, it cannot, in the absence of the F2 domain, reach its native conformation. However, its association with the anti-native-beta 2 antibody induces a structural change of F1 that brings it closer to the conformation it normally adopts when interacting with F2 inside the native beta 2 subunit.
Synthesis of inositol 1,2-(cyclic)-4,5-trisphosphate.
Authors: Auchus R J , Kaiser S L , Majerus P W
Published: May 2006

We have developed a method for synthesis of inositol 1,2-(cyclic)-4,5-trisphosphate from inositol 1,4,5-trisphosphate using a water-soluble carbodiimide. We obtained 1-1.5 mumol of the inositol cyclic trisphosphate starting with 5 mumol of inositol 1,4,5-trisphosphate. The cyclized product was isolated by HPLC on Partisil SAX. The identity of the cyclic product was verified by its hydrolysis to inositol 1,4,5-trisphosphate in acid and by its conversion to 1,2-(cyclic)-4-bisphosphate by a specific 5-phosphomonoesterase from platelets. We also identified the product by 31P NMR spectroscopy, which showed a peak at 17.2 ppm, characteristic of a five-membered cyclic phosphodiester ring, and peaks at 4.1 ppm and 0.8 ppm, indicative of phosphomonoesters. This relatively simple method for producing inositol 1,2-(cyclic)-4,5-trisphosphate will facilitate studies of the physiology of this compound in signal transduction.
Evolutionary relationship between the natural anti-Gal antibody and the Gal alpha 1----3Gal epitope in primates.
Authors: Galili U , Clark M R , Shohet S B , Buehler J , Macher B A
Published: May 2006

Anti-Gal is a natural antibody, which constitutes as much as 1% of circulating IgG in humans and displays a distinct specificity for the structure Gal alpha 1----3Gal. This glycosidic structure has been found on various tissues of many nonprimate mammals. A comparative study of the occurrence of anti-Gal versus the expression of the Gal alpha 1----3Gal epitope was performed in primates, and a distinct evolutionary pattern was observed. Whereas anti-Gal was found to be present in Old World monkeys and apes in titers comparable to those in humans, its corresponding antigenic epitope is abundantly expressed on erythrocytes of New World monkeys. Immunostaining with anti-Gal of glycolipids from New World monkey erythrocytes indicated that the molecules to which anti-Gal binds are similar to those found in rabbit and bovine erythrocytes. These findings indicate that there is an evolutionary reciprocity between New World and Old World primates in the production of the Gal alpha 1----3Gal structure and the antibody that recognizes it. The expression of the Gal alpha 1----3Gal epitope was evolutionarily conserved in New World monkeys, but it was suppressed in ancestral lineages of Old World primates. The suppression of this epitope was accompanied by the production of anti-Gal. The observed in vivo binding of anti-Gal to human normal senescent and some pathologic erythrocytes implies that the Gal alpha 1----3Gal epitope is present in man in a cryptic form.
Identification of a monoclonal antibody specific for a murine T3 polypeptide.
Authors: Leo O , Foo M , Sachs D H , Samelson L E , Bluestone J A
Published: May 2006

A monoclonal antibody (145-2C11) specific for the murine T3 complex was derived by immunizing Armenian hamsters with a murine cytolytic T-cell clone. The antibody is specific for a 25-kDa protein component (T3-epsilon) of the antigen-specific T-cell receptor. It reacts with all mature T cells and can both activate and inhibit T-cell function. These results identify T3-epsilon as a cell surface protein involved in the transduction of activation signals.
Synthetic gene construct expressing a repeated and highly immunogenic epitope of the Plasmodium falciparum antigen Pf155.
Authors: Aslund L , Sjölander A , Wahlgren M , Wåhlin B , Ruangjirachuporn W , Berzins K , Wigzell H , Perlmann P , Pettersson U
Published: May 2006

The Plasmodium falciparum-derived antigen Pf155 contains two blocks of tandemly repeated amino acid sequences. A pair of complementary oligonucleotides, encoding the C-terminally located repeat Val-Glu-His-Asp-Ala-Glu-Glu-Asn, were synthesized. The oligonucleotides were polymerized by ligation, and the resulting multimers were cloned into an expression vector. One construct that contained four copies of the repeat was expressed in Escherichia coli. The product, a fusion protein, was soluble and produced in high amounts. It reacted in immunoblotting with a monoclonal antibody to a synthetic octapeptide (Glu-Glu-Asn-Val-Glu-His-Asp-Ala). Rabbits immunized with partially purified fusion protein, either with or without adjuvant, formed antibodies against this octapeptide. These antibodies reacted with Pf155 both in parasite extracts and when deposited in the membrane of infected erythrocytes. Furthermore, these antibodies inhibited merozoite reinvasion in vitro as efficiently as human antibodies to the octapeptide sequence in Pf155, induced by natural infection. The results suggest that products of synthetic gene constructs may be a suitable basis for an anti-merozoite vaccine.
Basal and adenosine receptor-stimulated levels of cAMP are reduced in lymphocytes from alcoholic patients.
Authors: Diamond I , Wrubel B , Estrin W , Gordon A
Published: May 2006

Alcoholism causes serious neurologic disease that may be due, in part, to the ability of ethanol to interact with neural cell membranes and change neuronal function. Adenosine receptors are membrane-bound proteins that appear to mediate some of the effects of ethanol in the brain. Human lymphocytes also have adenosine receptors, and their activation causes increases in cAMP levels. To test the hypothesis that basal and adenosine receptor-stimulated cAMP levels in lymphocytes might be abnormal in alcoholism, we studied lymphocytes from 10 alcoholic subjects, 10 age- and sex-matched normal individuals, and 10 patients with nonalcoholic liver disease. Basal and adenosine receptor-stimulated cAMP levels were reduced 75% in lymphocytes from alcoholic subjects. Also, there was a 76% reduction in ethanol stimulation of cAMP accumulation in lymphocytes from alcoholics. Similar results were demonstrable in isolated T cells. Unlike other laboratory tests examined, these measurements appeared to distinguish alcoholics from normal subjects and from patients with nonalcoholic liver disease. Reduced basal and adenosine receptor-stimulated levels of cAMP in lymphocytes from alcoholics may reflect a change in cell membranes due either to chronic alcohol abuse or to a genetic predisposition unique to alcoholic subjects.
Aberrant splicing of proteolipid protein mRNA in the dysmyelinating jimpy mutant mouse.
Authors: Hudson L D , Berndt J A , Puckett C , Kozak C A , Lazzarini R A
Published: May 2006

cDNA clones encoding proteolipid protein (PLP) were isolated from a mouse brain library and sequenced. We describe two transcripts arising from the PLP locus by alternative splicing: the major one encodes the 277-amino acid PLP protein and the minor one corresponds to the DM-20 protein, a PLP-like protein of 20,000 Mr that shares both amino and carboxyl regions with PLP. These two transcripts lack approximately 70 bases in PLP mRNA from the dysmyelinating jimpy mutant. The deletion spans amino acids 208-232; however, this region is present in the jimpy PLP-encoding gene. We propose that the jimpy mutant suffers a point mutation or the deletion of a few bases in the PLP gene that alters the normal splicing pattern and generates partially deleted PLP transcripts.
Possible origin of a calmodulin gene that lacks intervening sequences.
Authors: Gruskin K D , Smith T F , Goodman M
Published: May 2006

The divergent, muscle-specific allele of the chicken calmodulin gene contains no intervening sequences and apparently was produced by a reverse transcriptase-mediated event. The nucleotide and deduced amino acid sequences of this gene were compared with nucleotide and amino acid sequence data of other known calmodulin genes in order to investigate its evolutionary history. These comparisons, as well as the CpG dinucleotide content, support the conclusion that this highly divergent chicken calmodulin gene did not exist for any significant period of times as a pseudogene and suggest plausible alternative genetic histories. The most parsimonious history involves the viral import of a very old foreign gene of high CpG content.
Ferric chloride-catalyzed activation of hydrogen peroxide for the demethylation of N,N-dimethylaniline, the epoxidation of olefins, and the oxidative cleavage of vicinal diols in acetonitrile: a reaction mimic for cytochrome P-450.
Authors: Sugimoto H , Spencer L , Sawyer D T
Published: May 2006

In dry acetonitrile, anhydrous Fe(III)Cl3 catalyzes the demethylation of N,N-dimethylaniline, the epoxidation of olefins, and the oxidative cleavage of 1-phenyl-1,2-ethanediol (and other 1,2-diols) by hydrogen peroxide. For each class of substrate the products closely parallel those that result from their enzymatic oxidation by cytochrome P-450. Because of the close congruence of products, the catalytic nature of the Fe(III)Cl3/H2O2 reaction mimic, and the similarity of the dipolar aprotic solvent (acetonitrile) to the proteinaceous lipid matrix of the biomembrane, the form of the reactive intermediate may be the same in each case. A mechanism is proposed in which an initial Lewis acid-base interaction of Fe(III)Cl3 with H2O2 generates a highly electrophilic Fe(III)-oxene species as the reactive intermediate. This is in contrast to the prevailing view that cytochrome P-450 acts as a redox catalyst to generate an Fe(V)-oxo species or an Fe(IV)-oxo cation radical as the reactive intermediate.
Increased rates of decay and reduced levels of accumulation of the major poly(A)-associated proteins of Dictyostelium during heat shock and development.
Authors: Manrow R E , Jacobson A
Published: May 2006

Two major polypeptide species, 31,000 Mr (p31) and 31,500 Mr (p31.5), are associated with the 3' poly(A) tails of Dictyostelium mRNAs. We have measured the accumulation of newly synthesized p31 and p31.5 and the decay of preexisting p31 and p31.5 during heat shock and early development. Only trace amounts of newly synthesized p31 and p31.5 accumulate at elevated temperatures, indicating that these polypeptides are not heat shock proteins. In addition, preexisting p31 and p31.5 are rapidly degraded in heat-shocked cells. This degradation is selective and occurs simultaneously with a sharp drop in the rate of translational initiation. Similarly, in early development, a time when the rate of translational initiation is also sharply reduced, only trace amounts of newly synthesized p31 and p31.5 accumulate and most of the preexisting p31 and p31.5 is rapidly degraded. When translational elongation is inhibited with cycloheximide, preexisting p31 and p31.5 remain stable. Therefore, a correlation seems to exist between the abundance and stability of these poly(A)-associated proteins and the rate of translational initiation. Our results are consistent with the proposed role of the poly(A)-protein complex in translation and do not support the findings of Schönfelder et al. [Schönfelder, M., Horsch, A. & Schmid, H.-P. (1985) Proc. Natl. Acad. Sci. USA 82, 6884-6888] that the 73,000 Mr HeLa cell poly(A)-binding protein and the major 73,000 Mr mammalian heat shock protein (i.e., hsp70) are identical.
cDNA cloning and sequence of MAL, a hydrophobic protein associated with human T-cell differentiation.
Authors: Alonso M A , Weissman S M
Published: May 2006

We have isolated a human cDNA that is expressed in the intermediate and late stages of T-cell differentiation. The cDNA encodes a highly hydrophobic protein, termed MAL, that lacks a hydrophobic leader peptide sequence and contains four potential transmembrane domains separated by short hydrophilic segments. The predicted configuration of the MAL protein resembles the structure of integral proteins that form pores or channels in the plasma membrane and that are believed to act as transporters of water-soluble molecules and ions across the lipid bilayer. The presence of MAL mRNA in a panel of T-cell lines that express both the T-cell receptor and the T11 antigen suggests that MAL may be involved in membrane signaling in T cells activated via either T11 or T-cell receptor pathways.
cDNA cloning of human myeloperoxidase: decrease in myeloperoxidase mRNA upon induction of HL-60 cells.
Authors: Weil S C , Rosner G L , Reid M S , Chisholm R L , Farber N M , Spitznagel J K , Swanson M S
Published: May 2006

Myeloperoxidase (MPO), the most abundant neutrophil protein, is a bacteriocidal component of the primary granules and a critical marker in distinguishing acute myelogenous leukemia from acute lymphoid leukemia. A cDNA clone for human MPO was isolated by immunologic screening of human hematopoietic lambda gt11 expression vector libraries with specific anti-MPO antibody. The identity of the cDNA clone was confirmed by finding that epitope-selected antibody against this clone recognizes purified MPO and MPO in human promyelocytic (HL-60) cell lysates by immunoblot analysis, and that hybrid selection of HL-60 mRNA with this cDNA clone and translation in vitro results in the synthesis of an 80-kDa protein recognized by the anti-MPO antiserum. RNA blot analysis with this MPO cDNA clone detects hybridization to two polyadenylylated transcripts of approximately 3.6 and approximately 2.9 kilobases in HL-60 cells. No hybridization is detected to human placenta mRNA. Upon induction of HL-60 cells to differentiate by incubation for 4 days with dimethyl sulfoxide, a drastic decrease in the hybridization intensity of these two bands is seen. This is consistent with previous data suggesting a decrease in MPO synthesis upon such induction of these cells. The MPO cDNA should be useful for further molecular and genetic characterization of MPO and its expression and biosynthesis in normal and leukemic granulocytic differentiation.
Structure and expression of the rat neuropeptide Y gene.
Authors: Larhammar D , Ericsson A , Persson H
Published: May 2006

Neuropeptide Y is a 36-amino acid peptide that is abundant throughout the mammalian nervous system. It belongs to the same family of carboxyl-terminally amidated peptides as pancreatic polypeptide and peptide YY. We describe here the gene encoding the rat neuropeptide Y precursor. The gene spans 7.2 kilobase pairs and contains four exons. The exon organization is identical to the pancreatic polypeptide gene, although the amino acid sequences of the neuropeptide Y and pancreatic polypeptide precursors differ extensively. The predicted amino acid sequence of mature rat neuropeptide Y is identical to the human sequence. Also the sequence of the 30-amino acid carboxyl-terminal peptide of preproneuropeptide Y is highly conserved, which suggests that it is functionally important. Two neuropeptide Y alleles were found to differ at nine positions in 2.5 kilobase pairs at the 5' portion of the gene. No exon difference was found. One nucleotide substitution close to the gene promoter may influence the regulation of expression. Neuropeptide Y mRNA was found in all rat brain subregions tested, which shows that neuropeptide Y is synthesized throughout the brain. Developmentally, mRNA was detected in the rat brain as early as embryonic day 16 and increased rapidly to adult levels. The level of neuropeptide Y mRNA was also studied in several rat peripheral organs. Unexpectedly high levels were observed in heart and spleen. This mRNA may be synthesized in intrinsic ganglia and non-neuronal cells, respectively.
Asymptotically minimax stochastic search strategies in the plane
Authors: Lalley Steven , Robbins Herbert
Published: May 2006

Stochastic search strategies are proposed for finding a possibly mobile target within a convex region of the plane. The strategies are asymptotically minimax as ε → 0 with respect to the time required to get within ε of the target.
High-affinity interleukin 2 binding by an oncogenic hybrid interleukin 2-epidermal growth factor receptor molecule.
Authors: Bernard O , Fazekas de St Groth B , Ullrich A , Green W , Schlessinger J
Published: May 2006

Both interleukin 2 (IL-2) and epidermal growth factor (EGF) receptors exist in two forms that differ with respect to affinity for their ligand. Only the high-affinity receptors appear to be responsible for the proliferation signal delivered upon binding of the growth factor. Fibroblasts transfected with IL-2 receptor cDNA generate only low-affinity receptors for IL-2, but fusion of membranes from these fibroblasts with T-cell membranes converts some receptors to high affinity, indicating the involvement of a T cell-specific factor in the generation of high-affinity receptors. We have constructed a chimeric cDNA molecule containing the extracellular IL-2-binding domain of the IL-2 receptor cDNA and the transmembrane and intracellular tyrosine kinase domains of the EGF receptor cDNA. When transfected into fibroblasts, this IL-2-EGF receptor cDNA generated high-affinity receptors for IL-2. Moreover, fibroblasts transfected with the chimeric molecule were morphologically transformed and produced rapidly growing tumors in nude mice.
Protein glycosylation in yeast: transcript heterogeneity of the ALG7 gene.
Authors: Kukuruzinska M A , Robbins P W
Published: May 2006

The first enzyme in the lipid-linked oligosaccharide biosynthetic pathway, UDP-N-acetylglucosamine-dolichyl-phosphate N-acetylglucosaminephosphotransferase (UDP-N-acetyl-D-glucosamine:dolichyl-phosphate-N-acetyl- D-glucosaminephosphotransferase, EC 2.7.8.15), is encoded by the ALG7 gene. We show that this gene is essential for cell growth, since a null mutation constructed with standard gene disruption techniques results in cell lethality. The ALG7 gene is transcribed into two major messages, approximately 1.38 and 1.56 kilobase pairs (kbp) in size, and this heterogeneity has been mapped to the 3' untranslated region. Two sets of tripartite sequences implicated in transcription termination begin 15 bp and 256 bp past the translation stop codon, TGA. The ratios of the two major transcripts change with gene dosage, with the longer mRNA becoming more abundant in cells containing higher levels of the ALG7 gene. Changes in transcript ratios are also observed in mutants defective in lipid-linked sugar-donor biosynthesis. In addition, there is 5' heterogeneity in the ALG7 mRNAs. The transcripts start at four initiation sites located within a 20-bp region. Two potentially functional TATA elements have been identified at positions -157 and -139, which may be involved in initiation from multiple sites. These features point to numerous factors that may be involved in the regulation of the expression of the ALG7 gene.
Mutations in the 2-microns circle site-specific recombinase that abolish recombination without affecting substrate recognition.
Authors: Prasad P V , Young L J , Jayaram M
Published: May 2006

The site-specific recombinase encoded by the yeast plasmid 2-microns circle (FLP) forms a transient covalent linkage with its substrate DNA via a tyrosine residue, which appears to be located near its COOH terminus. The homology of the COOH terminus of FLP with that of the Int family of recombinases suggests that tyrosine-343 of FLP could be involved in forming the DNA-protein bridge. We have mutated tyrosine-343 to a phenylalanine or serine. We demonstrate that the binding of each of the two mutant proteins to its substrate is indistinguishable from that of wild-type FLP. However, both mutant proteins are incapable of catalyzing strand cleavage and recombination.
Cyclic AMP regulation of the human glycoprotein hormone alpha-subunit gene is mediated by an 18-base-pair element.
Authors: Silver B J , Bokar J A , Virgin J B , Vallen E A , Milsted A , Nilson J H
Published: May 2006

cAMP regulates transcription of the gene encoding the alpha-subunit of human chorionic gonadotropin (hCG) in choriocarcinoma cells (BeWo). To define the sequences required for regulation by cAMP, we inserted fragments from the 5' flanking region of the alpha-subunit gene into a test vector containing the simian virus 40 early promoter (devoid of its enhancer) linked to the bacterial chloramphenicol acetyltransferase (CAT) gene. Results from transient expression assays in BeWo cells indicated that a 1500-base-pair (bp) fragment conferred cAMP responsiveness on the CAT gene regardless of position or orientation of the insert relative to the viral promoter. A subfragment extending from position -169 to position -100 had the same effect on cAMP-induced expression. Furthermore, the entire stimulatory effect could be achieved with an 18-bp synthetic oligodeoxynucleotide corresponding to a direct repeat between positions -146 and -111. In the absence of cAMP, the alpha-subunit 5' flanking sequence also enhanced transcription from the simian virus 40 early promoter. We localized this enhancer activity to the same -169/-100 fragment containing the cAMP response element. The 18-bp element alone, however, had no effect on basal expression. Thus, this short DNA sequence serves as a cAMP response element and also functions independently of other promoter-regulatory elements located in the 5' flanking sequence of the alpha-subunit gene.
Cloning of the bovine 215-kDa cation-independent mannose 6-phosphate receptor.
Authors: Lobel P , Dahms N M , Breitmeyer J , Chirgwin J M , Kornfeld S
Published: May 2006

Four overlapping cDNA clones encoding a partial sequence of the cation-independent 215-kDa mannose 6-phosphate receptor have been identified by screening a fetal calf liver cDNA library with oligonucleotide probes. RNA hybridization analysis showed that the length of the mRNA is approximately 9.5 kilobases. Sequence analysis demonstrated that the clones consist of 4647 contiguous nucleotides and contain an open reading frame coding for a polypeptide of 1461 amino acids, which we estimate represents greater than 75% of the primary structure of the receptor. The deduced amino acid sequence indicates that the receptor has a carboxyl-terminal cytoplasmic domain of 163 amino acids that is rich in acidic residues, a 23-amino acid transmembrane segment, and an extracellular domain containing at least eight homologous repeats of approximately 145 amino acids. One of the repeats contains an additional 43-residue segment that is similar to the type II repeat of fibronectin. Each repeat contains a highly conserved 13-amino acid unit bordered by cysteine residues that may be functionally important.
Different mutations are responsible for the elevated sister-chromatid exchange frequencies characteristic of Bloom's syndrome and hamster EM9 cells.
Authors: Ray J H , Louie E , German J
Published: May 2006

Experimental hybridization of cultured cells was employed to determine whether the strikingly elevated rates of sister-chromatid exchange (SCE) exhibited by Bloom's syndrome (BS) and hamster cell line EM9 have the same or different bases. Seventeen cell lines were developed from polyethylene glycol-treated mixtures of BS and EM9 cells. Cytogenetic analysis proved the hybrid nature of 12 of the lines; 9 of those 12 exhibited low (normal) numbers of SCEs, signifying complementation. The parental BS and EM9 cells, although resembling each other in exhibiting very high SCE frequencies in BrdUrd-containing medium, differ from one another with respect to their proliferative abilities in such medium, the EM9 cells but not the BS cells being exquisitely hypersensitive to BrdUrd. In the low-SCE hybrid lines, hypersensitivity to growth in BrdUrd-containing medium was restored to normal whereas the hypersensitivity was retained by the high-SCE hybrids. It is concluded, first, that the mutations in BS and EM9 cells are different and, second, that both the elevated SCE frequency and the excessive BrdUrd hypersensitivity of EM9 cells are due to the same mutation.
Thy-1+ dendritic epidermal cells belong to the T-cell lineage.
Authors: Stingl G , Gunter K C , Tschachler E , Yamada H , Lechler R I , Yokoyama W M , Steiner G , Germain R N , Shevach E M
Published: May 2006

The murine epidermis contains a population of dendritic, Thy-1+ cells (Thy-1+ DEC). Although it is now clear that these cells are of bone marrow origin, extensive morphological, histochemical, and cell-membrane marker studies have not definitively placed them in any known hematopoietic differentiation pathway. Based on the observation that Thy-1+ DEC can be propagated in vitro with Con A and interleukin 2, we have established three cell lines (Tehy 184, Tehy 245, and Yety 245) that can be continuously grown in medium with lectin-lymphokine-rich culture supernatants of rat spleen cells. With the exception of the loss of reactivity with anti-asialo-GM1 antibodies (Tehy 184 and Tehy 245) and the gain of interleukin 2 receptor expression, the cultured cell lines bear the same surface characteristics as freshly isolated Thy-1+ DEC: Thy-1+, Ly-5+, Lyt-1-, Lyt-2-, L3T4-, Ia-, sIg-. Using Southern and RNA gel blot analysis, we now demonstrate that these Thy-1+ DEC-derived cell lines exhibit various patterns of rearrangements in the gene complexes encoding the T-cell receptor (related) beta and gamma chains and contain mature and/or incomplete transcripts from the T-cell receptor alpha- and beta-chain genes, as well as transcripts from the receptor-related gamma-chain genes. Tehy 184 cells, the only cells containing both mature alpha- and beta-chain transcripts, react positively with the F23.1 monoclonal antibody, which recognizes the product of a subset of T-cell receptor beta-chain variable region gene segments. This antibody precipitates a surface protein of 84-88 kDa from these cells that after reduction separates into two 40- to 44-kDa chains, characteristic of Ti alpha/beta heterodimers. These data strongly suggest that Thy-1+ DEC belong to the T-cell lineage and point to the epidermis as a site either of immature thymocyte migration or of extrathymic T-cell differentiation.
In vivo stimulation of granulopoiesis by recombinant human granulocyte colony-stimulating factor.
Authors: Cohen A M , Zsebo K M , Inoue H , Hines D , Boone T C , Chazin V R , Tsai L , Ritch T , Souza L M
Published: May 2006

Osmotic pumps containing Escherichia coli-derived recombinant human granulocyte colony-stimulating factor (rhG-CSF) were attached to indwelling jugular vein catheters and implanted subcutaneously into Golden Syrian hamsters. Within 3 days, peripheral granulocyte counts had increased greater than 10-fold with a concomitant 4-fold increase in total leukocytes. Microscopic examination of Wright-Giemsa-stained blood smears from rhG-CSF hamsters showed that only the neutrophil subpopulation of granulocytes had increased. No significant changes in lymphocyte or monocyte counts were observed during the course of continuous rhG-CSF treatment. After subcutaneous injection at rhG-CSF doses of up to 10 micrograms X kg-1 X day-1 only granulocyte counts were affected. However, at higher dose levels, a transient thrombocytopenia was noted. Erythrocyte had lymphocyte/monocyte counts remained unaffected by rhG-CSF over the entire dose range (0.3-300 micrograms X kg-1 X day-1) studied. Total leukocyte counts increased 3-fold within 12 hr after a single s.c. injection of rhG-CSF. This early effect was associated with an increase in the total number of colony-forming cells and the percent of active cycling cells in the marrow. A sustained elevation of peripheral leukocyte and marrow progenitor counts was observed following seven daily s.c. injections of rhG-CSF. The ability of rhG-CSF to increase the production and release of granulocytes from the marrow may underlie the beneficial effect it produced on the restoration of peripheral leukocyte counts in hamsters made leukopenic by treatment with 5-fluorouracil.
Superactive octapeptide somatostatin analogs containing tryptophan at position 1.
Authors: Cai R Z , Karashima T , Guoth J , Szoke B , Olsen D , Schally A V
Published: May 2006

We synthesized a series of octapeptide analogs of somatostatin, containing N-terminal tryptophan or another amino acid followed by the hexapeptide sequences Cys-Phe-D-Trp-Lys-Thr-Cys or Cys-Tyr-D-Trp-Lys-Val-Cys and a C-terminal threoninamide or tryptophanamide. After purification by HPLC, the inhibitory activities of these analogs on the release of growth hormone (somatotropin) in rats were determined in vivo. The eight octapeptides with an N-terminal tryptophan residue were found to have a greater inhibitory effect than somatostatin. The most potent of these analogs, D-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, was 94.3 times more active than somatostatin. The other analogs, in order of decreasing potency, were Ac-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, D-Trp(For)-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, D-Trp-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-NH2, Ac-Trp(For)-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, Ac-Trp-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-NH2, D-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Trp-NH2, and D-Trp-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2. The growth hormone inhibitory activity of these analogs was from 53.7 to 11.6 times greater than that of somatostatin. The octapeptides containing D- or L-tryptophan at the N-terminus, phenylalanine at position 3, and threonine at position 6 exhibited a greater inhibitory effect on growth hormone release than that of the analogs with tyrosine and valine at positions 3 and 6, respectively. Substitution of D-tryptophan for D-phenylalanine at the N-terminus in the octapeptide containing phenylalanine in the third, threonine in the sixth, and threoninamide in the C-terminal position also increased the growth hormone-release inhibitory activity. Time-course assay showed that D-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2 (RC-98-I), in a dose of 1 microgram/kg of body weight, inhibited the release of growth hormone for at least 3 hr. In view of their high activity and prolonged duration of action, some of these analogs could be useful clinically.
Escherichia coli DnaX product, the tau subunit of DNA polymerase III, is a multifunctional protein with single-stranded DNA-dependent ATPase activity.
Authors: Lee S H , Walker J R
Published: May 2006

The dnaZX gene of Escherichia coli directs the synthesis of two proteins, DnaZ and DnaX. These products are confirmed as the gamma and tau subunits of DNA polymerase III because antibody to a synthetic peptide present in both the DnaZ and DnaX proteins reacts also with the gamma and tau subunits of holoenzyme. To characterize biochemically the tau subunit, for which there has been no activity assay, the dnaZX gene was fused to the beta-galactosidase gene to encode a fusion product in which the 20 C-terminal amino acids of the DnaX protein (tau) were replaced by beta-galactosidase lacking only 7 N-terminal amino acids. The 185-kDa fusion protein, which retained beta-galactosidase activity, was overproduced to the level of about 5% of the soluble cellular protein by placing the gene fusion under control of the tac promoter and Shine-Dalgarno sequence. The fusion protein was isolated in one step by affinity chromatography on p-aminobenzyl 1-thio-beta-D-galactopyranoside-agarose. The purified fusion protein also had ATPase (and dATPase) activity that was dependent on single-stranded DNA. This activity copurified with the beta-galactosidase activity not only through the affinity column but also through a subsequent gel filtration. We conclude that the DnaX protein function involves binding to single-stranded DNA and hydrolysis of ATP or dATP, in addition to binding to other DNA polymerase III holoenzyme components, increasing the processivity of the core enzyme, and serving as a substrate for the production of the gamma subunit.
Rous sarcoma virus is integrated but not expressed in chicken early embryonic cells.
Authors: Mitrani E , Coffin J , Boedtker H , Doty P
Published: May 2006

We have developed a protocol that allows us to infect chicken early embryonic (CEE) cells with high efficiency. This was achieved by exposing the CEE cells to a semicontinuous dose of Rous sarcoma virus (RSV) for a period of 20 hr. Southern blot analysis indicated that an average of one proviral copy is integrated per embryonic cell. However, there was no production of infectious viral particles by the cells containing the proviral genome, although low levels of full-length genomic RNA could be detected by RNA transfer blot analysis. These low RNA levels contrast with the 100- to 1000-fold higher levels found in RSV-infected chicken embryo fibroblasts. We conclude that in cells derived from pregastrulating chicken embryos, RSV DNA is integrated into the cell genome but fails to be expressed in an efficient manner. These primary cells can therefore be used to identify factors involved in regulation of retroviral gene expression in normal cells. Such factors may also be instrumental in elucidating basic mechanisms involved in gene regulation during early development in higher vertebrates.
Avian sarcoma virus 17 carries the jun oncogene.
Authors: Maki Y , Bos T J , Davis C , Starbuck M , Vogt P K
Published: May 2006

Biologically active molecular clones of avian sarcoma virus 17 (ASV 17) contain a replication-defective proviral genome of 3.5 kilobases (kb). The genome retains partial gag and env sequences, which flank a cell-derived putative oncogene of 0.93 kb, termed jun. The jun gene lacks preserved coding domains of tyrosine-specific protein kinases. It also shows no significant nucleic acid homology with other known oncogenes. The probable transformation-specific protein in ASV 17-transformed cells is a 55-kDa gag-jun fusion product.
Mutation to male fertility and toxin insensitivity in Texas (T)-cytoplasm maize is associated with a frameshift in a mitochondrial open reading frame
Authors: Wise Roger P. , Pring Daryl R. , Gengenbach Burle G.
Published: May 2006

Tissue culture-derived mutants of male-sterile and disease toxin-sensitive Texas (T)-cytoplasm maize that exhibit male fertility and toxin insensitivity carry numerous alterations in mitochondrial DNA. In these mutants, a 6.7-kilobase
Xho
I fragment characteristic of parental T cytoplasm has been rearranged. In the mutant T-4, the parental 6.7-kilobase
Xho
I fragment contains a guanine to adenine transition adjacent to a 5-base-pair insertion not found in T cytoplasm. The insertion, internal to a 345-base-pair open reading frame (T ORF13), generates a frameshift, resulting in a premature stop codon that terminates the open reading frame at base pair 222. In other mutants, the 345-base-pair ORF is part of a 3-kilobase deletion, which extends into a 5-kilobase repeat characteristic of mtDNA from T but not N male-fertile cytoplasm. Clones specific to T ORF13 hybridize to eight transcripts in T and T-4, yet only hybridize to three transcripts in T-7, a deletion mutant. Transcription of the T ORF13 region appears not to be altered in T-4, but the frameshift mutation in the T ORF13 reading frame indicates that a biologically inactive gene product could be associated with the mutational events. The results suggest that cytoplasmic male sterility and disease toxin sensitivity may be associated with presence of T ORF13 in T-cytoplasm maize.