bluuebunny/crossref_metadata_2025 huggingface dataset:
A Polypeptide Region of Bovine Prothrombin Specific for Binding to Phospholipids
Authors: Gitel Sanford N. , Owen Whyte G. , Esmon Charles T. , Jackson Craig M.
Published: May 2006

The blood-clotting protein prothrombin can be converted to thrombin in free solution by the proteolytic enzyme, activated factor X. When prothrombin is bound to the surface of phospholipid vesicles, the rate of thrombin generation is increased more than 30-fold over the rate of unbound prothrombin. If the prothrombin activation process is terminated after a time interval in which less than 10% of the expected thrombin has been produced, two major products are found in the activation mixture. These products have been termed intermediate 1, a precursor of thrombin, and fragment 1. The conversion of intermediate 1 to thrombin is not accelerated by phospholipid nor can binding of this intermediate to phospholipid particles be demonstrated. In contrast, fragment 1, the other activation product derived from prothrombin, binds to phospholipid particles under the same conditions as prothrombin. On the basis of these observations, we propose that the prothrombin molecule contains a specific region of polypeptide chain for binding to phospholipid particles. This specific polypeptide region or lipid interaction site is part of the nonthrombin-forming activation fragment.
Sequence Homology at the 5′-Termini of Insect Messenger RNAs
Authors: Ilan Joseph , Ilan Judith
Published: May 2006

Treatment of insect polyribosomes with 1 M KCl released a messenger ribonucleoprotein with a pronounced 16S peak. Phenol extraction resulted in a defined peak of 10S RNA, which was judged as mRNA by the following criteria: it showed specificity for binding to ribosomes, and the formation of initiation complex was dependent on protein initiation factors, GTP, mRNA, and aminoacyl-tRNA. The complex directed protein synthesis upon the addition of elongation factors. mRNA was treated with phosphatase and phosphorylated at the 5′-end with [
32
P]cyanoethylphosphate. [
32
P]mRNA was digested by T1 ribonuclease to completion and chromatographed on DEAE-cellulose. The only fragment with
32
P was 15 nucleotides long; it was treated with pancreatic ribonuclease and fingerprinted. Fractions of AC, AAC, and AAAC were found. Initiation signal AUG or GUG in these mRNAs does not begin immediately at the 5′-end and may be at a distance greater than 15 nucleotides. Alkaline hydrolysis of mRNAs labeled
in vivo
with [
14
C]adenosine revealed Ap and pppAp. Alkaline hydrolysis of mRNA labeled with
32
P at the 5′-terminus resulted in pAp. Hence, these results suggest that in a heterogeneous population of mRNAs from insects, all start with A and have sequence homology at the 5′-termini. This sequence may reflect the signal for RNA polymerase on the gene or may promote the binding of mRNA to ribosomes.
Stimulation of Eukaryotic DNA-Dependent RNA Polymerase by Protein Factors
Authors: Lee Sheng-Chung , Dahmus Michael E.
Published: May 2006

Protein factors that stimulate DNA-dependent RNA polymerase activity
in vitro
have been purified from Novikoff ascites cells. These factors are not adsorbed by the diethylaminoethylcellulose column used for RNA polymerase purification and appear in the flow-through fraction. They can be fractionated into two classes by chromatography on carboxymethylcellulose. The first peak of activity elutes at 0.1 M NH
4
Cl, is stable to heat treatment of 100° for 5 min, and is designated heat-stable factor; the second peak of activity elutes at 0.3 M NH
4
Cl, is heat labile, and is designated heat-labile factor. Heat-labile factor can be further resolved into two components by chromatography on phosphocellulose. The heat-stable factor and second heat-labile factor stimulate the activity of (Novikoff ascites) RNA polymerase B by several-fold, and appear to function independently. RNA synthesis is stimulated only with native DNA as a template. No stimulation of
Escherichia coli
RNA polymerase is observed with any of the factors.
Association of the
r
IIA Protein with the Bacterial Membrane
Authors: Ennis Herbert L. , Kievitt Katharine D.
Published: May 2006

Cell membrane proteins synthesized after infection of
Escherichia coli
B with wild-type phage T4 and
r
IIA mutants were analyzed by dodecyl sulfate-polyacrylamide gel electrophoresis. A protein with an approximate molecular weight of 74,000 is present in membranes isolated from T4r
+
-infected cells, but is not found in membranes prepared from cells infected with an
r
IIA mutant in which the major part of the
r
IIA cistron is deleted. In addition, infection of
E. coli
B with different
r
IIA amber mutants and deletions gives peptides, which are associated with the bacterial membrane, of molecular weights consistent with the location of the respective mutations in the cistron. The
r
IIA protein is synthesized with delayed early kinetics. The synthesis of the
r
IIB protein, which is also located in the membrane, is not affected by mutations in the A cistron; conversely, synthesis of the
r
IIA protein is not affected by mutations in the B cistron. A mutant (
r
II 1589) contains a deletion that originates in the A cistron and extends into the adjacent B cistron. This mutant directs the synthesis of a compound membrane protein consisting of the undeleted portions of the A and B cistrons. The synthesis of the compound protein appears to be under the control of the A promoter.
Atypical Pattern of Utilization of Amino Acids for Mitochondrial Protein Synthesis in HeLa Cells
Authors: Costantino Paolo , Attardi Giuseppe
Published: May 2006

The capacity of HeLa cell mitochondria, either isolated or in intact cells, to incorporate different labeled amino acids into proteins was investigated. Eight amino acids (alanine, arginine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, and lysine), which include most of the charged polar ones, showed a very low amount, if any at all, of chloramphenicol-sensitive incorporation, relative to that expected for an “average” HeLa-cell protein. By contrast, the most hydrophobic amino acids (leucine, isoleucine, valine, phenylalanine, and methionine) were the most actively incorporated by HeLa mitochondria. The available evidence suggests that pool effects cannot account for this general pattern of utilization of amino acids; furthermore, this pattern is in good agreement with the known hydrophobic properties of proteins synthesized in mitochondria.
Papain-Solubilized HL-A Antigens from Cultured Human Lymphocytes Contain Two Peptide Fragments
Authors: Cresswell Peter , Turner Mervyn J. , Strominger Jack L.
Published: May 2006

HL-A 2 and HL-A 7 antigens have been solubilized from cultured human lymphocytes by papain and purified on a small radioactive scale after formation of immune complexes, or on a large scale by column chromatographic methods. In both cases, it has been shown that the materials obtained consist of two noncovalently bound fragments. One fragment is a glycopeptide of molecular weight 30,000-31,000, the other is a peptide of molecular weight 11,000-12,000. In polyacrylamide gels containing 8 M urea, the large fragments of HL-A 2 and HL-A 7 exhibited different electrophoretic mobilities, while the small fragments were the same. The relationship of these materials to the native HL-A molecule is discussed.
Ca
2+
Transport by Mitochondria from L1210 Mouse Ascites Tumor Cells
Authors: Reynafarje Baltazar , Lehninger Albert L.
Published: May 2006

Mitochondria isolated from the ascites form of L1210 mouse leukemia cells readily accumulate Ca
2+
from the suspending medium and eject H
+
during oxidation of succinate in the presence of phosphate and Mg
2+
, with normal stoichiometry between Ca
2+
uptake and electron transport. Ca
2+
loads up to 1600 ng-atoms per mg of protein are attained. As is the case in mitochondria from normal tissues, Ca
2+
uptake takes precedence over oxidative phosphorylation. However, Ca
2+
transport by the L-1210 mitochondria is unusual in other respects, which may possibly have general significance in tumor cells. The apparent affinity of the L1210 mitochondria for Ca
2+
in stimulation of oxygen uptake is about 3-fold greater than in normal liver mitochondria; moreover, the maximal rate of Ca
2+
transport is also considerably higher. Furthermore, when Ca
2+
pulses are added to L1210 mitochondria in the absence of phosphate or other permeant anions, much larger amounts of Ca
2+
are bound and H
+
ejected per atom of oxygen consumed than in the presence of phosphate; up to 7 Ca
2+
ions are bound per pair of electrons passing each energy-conserving site of the electron-transport chain. Such “superstoichiometry” of Ca
2+
uptake can be accounted for by two distinct types of respiration-dependent interaction of Ca
2+
with the L1210 mitochondria. One is the stimulation of oxygen consumption, which is achieved by relatively low concentrations of Ca
2+
(

K
m

≅ 8 μM) and is accompanied by binding of Ca
2+
up to 40 ng-atoms per mg of protein. The second process, also dependent on electron transport, is the binding of further Ca
2+
from the medium in exchange with previously stored membrane-bound protons, in which the affinity for Ca
2+
is much lower (

K
m

≅ 120 μM).
Maximal Functions and

H
p

Spaces Defined by Ergodic Transformations
Authors: Coifman Ronald R. , Weiss Guido
Published: May 2006

Suppose an ergodic flow acts on a probability space 𝔐 enabling us to introduce the Ergodic Hilbert transform
f̃
of
f
∈

L
p

(𝔐), 1 ≦
p
≦ ∞.
H
1
is the class of all functions of the form
f
+
if̃
∈
L
1
(𝔐). We show that
H
1
can be characterized in terms of a class of maximal functions; moreover, the dual space of
H
1
is identified with a space of functions of bounded mean oscillation defined in terms of the flow.
Origin and Direction of Replication of Bacteriophage 186 DNA
Authors: Chattoraj Dhruba K. , Inman Ross B.
Published: May 2006

Intracellular bacteriophage 186 DNA replicates as a single-branched circle during the first round of replication. The free end of the branch is located at a unique position with respect to phage 186 DNA base sequence, and this point should, therefore, correspond to the origin of DNA replication. The position of the growing point has been mapped at various degrees of replication, and found to move unidirectionally from left to right with respect to the denaturation map of phage 186 DNA.

A small proportion of the replicating molecules have two linear branches connected to the circle at two different branch points. These structures are consistent with two separate initiations from the same origin, again, with a unidirectional mode of replication. Branch points frequently have a single-stranded connection between the circle and the branch; significant numbers of branch points also possess an extra short single-stranded “whisker” protruding out of the branch point.
Aminoacid Sequence of Dogfish M
4
Lactate Dehydrogenase
Authors: Taylor Susan S. , Oxley Susanna S. , Allison William S. , Kaplan Nathan O.
Published: May 2006

About 80% of the aminoacid sequence of dogfish (
Squalus acanthius
) M
4
lactate dehydrogenase (EC 1.1.1.27) has been elucidated. Several sequence homologies with peptides from pig H
4
and pig M
4
lactate dehydrogenase are identified. Histidine 195 is homologous to the essential histidine residue in pig H
4
lactate dehydrogenase. Similarities in the sequence around the “essential” cysteine residue of lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and yeast and liver alcohol dehydrogenase are delineated.
Evolution of a Second Gene for β-Galactosidase in
Escherichia coli
Authors: Campbell John H. , Lengyel Judith A. , Langridge John
Published: May 2006

Mutants of
E. coli
K12 with deletions of the β-galactosidase gene (
lacZ
) can reacquire the ability to hydrolyze β-galactosides during prolonged intense selection for growth on lactose. Full lactose competence is restored through a sequence of at least five mutations. Cell extracts of these derived strains hydrolyze
o
-nitrophenyl-β-D-galactoside, the standard substrate for assay of β-galactosidase. The enzyme responsible for this activity differs in its immunological, kinetic, and sedimentation characteristics from the
lacZ
β-galactosidase of wild-type
E. coli
. Its genetic determinant, designated
ebg
-5, maps at 59 min on the
E. coli
chromosome, whereas the
lac
operon maps at 10 min. We suggest that a gene not involved in lactose utilization has been progressively changed into a form capable of specifying a β-galactosidase and that this process is similar to that whereby genes with new functions are evolved by natural selection.
Genetically Related Protein Variants Specifically Associated with Fruiting Body Maturation in
Neurospora
Authors: Nasrallah June Bowman , Srb Adrian M.
Published: May 2006

Electrophoretic analysis of fruiting body extracts from
Neurospora
reveals a characteristic protein, apparently absent in vegetative structures and ascospores, and which increases markedly in relative concentration after fertilization. Different wild-type species and strains studied have electrophoretic variants of this protein, two of which are shown to be controlled by members of an allelie pair.
Effect of Nalidixic Acid on DNA Replication by Toluene-Treated
Escherichia coli
Authors: Burger Richard M. , Glaser Donald A.
Published: May 2006

Nalidixic acid inhibits DNA synthesis in toluene-treated
E. coli
, strain B/r, as it is well known to do
in vivo
. Both semiconservative and repair syntheses are affected, though to different degrees. Density-transfer experiments indicate that chromosomal replication is reinitiated when nalidixic acid is removed from toluene-treated cells after exposure to the acid for one generation
in vivo
. For cells
in vivo
or after toluene-treatment, reinitiation is not seen in asynchronous cultures exposed briefly to nalidixic acid or in cells prevented from synthesizing proteins during their exposure to the acid. Reinitiation occurs at the chromosomal origin but, unlike the effect seen
in vivo
, replication at the old site persists.
In Vitro
Repression of Transcription of the Trytophan Operon by
trp
Repressor
Authors: Shimizu Yoshiko , Shimizu Nobuyoshi , Hayashi Masaki
Published: May 2006

The
in vitro
repression of transcription of the tryptophan operon by the
trp
repressor from
Escherichia coli
was studied. By measuring the inhibitory effect for
trp
-specific RNA synthesis in an
in vitro
transcription system directed by DNA of
trp
-transducing phage, we have detected and concentrated a
trp
repressor in an eluate of a Φ80 ptED native DNA-cellulose column. The repression of transcription of
trp
operon required the addition of L-tryptophan in the system, and when several tryptophan analogues were added, the repression or derepression was similar to that observed
in vivo
. The repressor fraction was separated from the majority of tryptophanyl-tRNA synthetase activity by Bio-gel P60 column chromatography.
The Role of a Tyrosyl Residue in the Mechanism of Action of Carboxypeptidase B: Luminescence Studies
Authors: Shaklai Nurith , Zisapel Nava , Sokolovsky Mordechai
Published: May 2006

The luminescence spectra of carboxypeptidase B indicate specific differences between the zinc and apoenzyme due to the state of tyrosyl residues presumably at the active site. These differences disappear when enzyme-substrate or enzyme-inhibitor complexes are formed, suggesting that they may reflect the interaction of a tyrosyl residue in the native enzyme with the catalytically essential zinc atom. An interpretation of the role of that tyrosyl residue in the mechanism of action of carboxypeptidase B is presented.
A Genetic Method for Determining the Order of Events in a Biological Pathway
Authors: Jarvik Jonathan , Botstein David
Published: May 2006

We describe the application of a simple genetic test that indicates the order of events in a morphogenic or biochemical pathway. The test uses temperature-sensitive (
ts
) and cold-sensitive (
cs
) mutants, and it orders the times at which the
ts
and
cs
defects are expressed.
Mutants of
Escherichia coli
Thermosensitive for the Synthesis of Transfer RNA
Authors: Schedl Paul , Primakoff Paul
Published: May 2006

Using a simple three-step procedure, we have isolated thermosensitive mutants of
E. coli
that are specifically defective in transfer RNA (tRNA) synthesis. Our procedure was designed to identify mutants that are unable to make su
3
+
tRNA
Tyr
or grow at the restrictive temperature, yet under the same conditions they retain the ability to make mRNA and protein. The mutants obtained have been analyzed, and they are defective in different steps in the synthesis of functional tRNA at the restrictive temperature. Some of them may fail to modify certain bases in the tRNA. Two mutants are unable to process the 5′ end of tRNA precursor molecules. Three are unable to cleave precursor molecules at the 3′ end. 11 Mutants can not synthesize any tRNA molecules or tRNA precursors. We speculate that these latter mutants may be defective in RNA polymerase or in an RNA polymerase factor specific for stable RNA synthesis.
Prophylaxis and Immunization in Mice by Use of Virus-Free Defective T Particles to Protect Against Intracerebral Infection by Vesicular Stomatitis Virus
Authors: Doyle Michael , Holland John J.
Published: May 2006

Defective interfering T particles of vesicular stomatitis virus provide remarkable protection against viral disease and death when introduced intracerebrally in large numbers along with an otherwise rapidly fatal low dose of standard infectious virus. This profound prophylactic effect of defective T particles is due to homologous autointerference since it is serotype-specific and interferon is not induced. This protective effect can be demonstrated only with preparations of T particles that have been purified completely free of infectious virions. When pure T particles are injected intracerebrally along with large doses of infectious virus, they convert an otherwise rapidly fatal disease process to a slowly progressing virus infection that generally terminates in death after many days of wasting disease and paralysis. Intracerebral injection of virus-free T particles alone is apparently innocuous to mice and stimulates immunity to massive doses of homologous infectious virus.

In vitro
, virus-free T particles at extremely high multiplicities depress cellular RNA and protein synthesis and kill BHK21 cells in culture, but do not exhibit such effects at moderately high multiplicities.
Identification of the Chloramphenicol-Binding Protein in
Escherichia coli
Ribosomes by Partial Reconstitution
Authors: Nierhaus Dagmar , Nierhaus Knud H.
Published: May 2006

50S-derived cores were prepared by treatment of 50S subunits with 0.4 M Licl (0.4c core) and 0.8 M Licl (0.8c core), respectively. 0.4c cores bind chloramphenicol whereas 0.8c cores do not. The split proteins obtained during the transitions 0.4c → 0.8c were separated by DEAE-cellulose chromatography and Sephadex G-100 gel filtration. Reconstitution experiments with the fractionated proteins demonstrated that protein L16 is involved in chloramphenicol binding.

In contrast to chloramphenicol, the CACCA-(
N
-acetyl-leucyl) fragment is bound by the 0.8c core, i.e., this core contains the intact
p
-site moiety of the peptidyltransferase center.

Puromycin can inhibit chloramphenicol binding completely. In the concentration range tested (up to 20 mM) the trinucleotide CCA inhibits chloramphenicol binding as effectively as puromycin, whereas an aminoacid mixture shows no inhibition. It is concluded that chloramphenicol acts exclusively on the
a
-site part of the peptidyltransferase center interfering with the binding of the last two or three nucleotides (3′ end) of aminoacyl-tRNA.
Theoretical Investigations of Automimicry: Multiple Trial Learning and the Palatability Spectrum
Authors: Pough F. Harvey , Brower Lincoln P. , Meck Harold R. , Kessell Stephen R.
Published: May 2006

We previously explored automimicry assuming that a species of prey was so unpalatable as to promote conditioned avoidance for a period of time after a predator encountered a single individual (
Case 1
). In this paper, we assume that the prey is less noxious and that two encounters are required.
Case 2
allows the two encounters with unpalatables to be separated by any number of palatables, while in
Case 3
the predator must encounter two unpalatables, consecutively.

The general relationships in the three cases are similar, but the automimetic advantage is reduced moderately in
Case 2
and greatly in
Case 3
. To attain the same automimetic advantage as in
Case 1
requires an increase in the proportion of unpalatables, or in the induced rejection period, or both. Consequently, selection will tend to increase the unpalatability so that
Cases 2
and
3
converge to
Case 1
.

Species that are uniformly and highly unpalatable can afford to be more dispersed than automimetic species.
Case-2
and
-3
automimetic species will benefit greatly from gregariousness, while in
Case-1
automimicry situations this is less important.
Enumeration of Activated Thymus-Derived Lymphocytes by the Virus Plaque Assay
Authors: Kano Shogo , Bloom Barry R. , Howe Michael L.
Published: May 2006

Lymphocytes activated by antigens or mitogens acquire the capacity to replicate viruses, and the number of activated lymphocytes can be estimated by the virus plaque assay. Concanavalin A and pokeweed mitogen produced 33-fold and 17-fold increases in virus plaqueforming cells (V-PFC), respectively, above background, while lipopolysaccharide produced only a 2- to 3-fold increase. T (thymus-derived lymphocyte)-depleted lymphocyte populations, derived from anti-θ-treated or nude (arthymic) mouse spleens, failed to produce V-PFC after culture with concanavalin A or pokeweed mitogen. The present studies thus demonstrate that the virus plaque assay measures activated T-lymphocytes.

A dissociation between the V-PFC response and cell proliferation was previously observed in antigen-stimulated cells cultured in the presence of mitotic inhibitors. In the present studies, while stimulation of CBA (H2
k
) lymphocytes by DBA/2 (H2
d
) cells produced high levels of thymidine incorporation, lymphocyte target-cell cytotoxicity, and V-PFC, stimulation of BALB/c (H2
d
) lymphocytes against DBA/2 (H2
d
) cells resulted in even higher levels of thymidine incorporation with a virtual absence of cytotoxic lymphocytes or V-PFC. These results indicate that proliferation is not a sufficient condition for permitting lymphocytes either to exert cytotoxicity on target cells or to replicate viruses, and suggest that there may be a correlation between the development of V-PFC and cytotoxic lymphocytes. They are consistent with the view that there are at least two functional subpopulations of T-lymphocytes.
Induction of the Allantoin Degradative Enzymes in
Saccharomyces cerevisiae
by the Last Intermediate of the Pathway
Authors: Cooper Terrance G. , Lawther Robert P.
Published: May 2006

Saccharomyces cerevisiae
can degrade allantoin in five steps to glyoxylate, ammonia, and “CO
2
.” We previously demonstrated that synthesis of the urea carboxylase-allophanate hydrolase multienzyme complex is contingent upon the presence of allophanic acid, the product of the urea carboxylase reaction. Since these enzymes catalyze the last two reactions of allantoin degradation, experiments were performed to establish whether or not the presence of allophanic acid was required for synthesis of any other enzymes participating in this degradative pathway. The data presented here indicate that allophanic acid is required for synthesis of all enzymes participating in allantoin degradation. This conclusion is based upon the observation that: (
i
) wild-type strains produced a large amount of allantoinase upon addition of allantoin, allantoate, ureidoglycolate, or urea to the medium, (
ii
) no increase in activity was observed unless the added compound could be metabolized to allophanate, (
iii
) strains lacking allophanate hydrolase contained large amounts of allantoinase even in the absence of added urea, and (
iv
) the urea analogue, formamide, was capable of inducing allantoinase synthesis in wild-type strains but would not serve this function in a strain lacking urea carboxylase.
Survival of Human Sickle-Cell Erythrocytes in Heterologous Species: Response to Variations in Oxygen Tension
Authors: Castro Oswaldo , Orlin Jerome , Rosen Michael W. , Finch Stuart C.
Published: May 2006

Survival characteristics, after transfusion, of erythrocytes from patients with homozygous sickle-cell disease were studied in rats. The study was made possible by previous injection of the animals with ethyl plamitate, which depressed reticuloendothelial system function, and with a factor in cobra venom that inactivated complement. This treatment prevented the rapid phagocytosis and intravascular hemolysis of donor erythrocytes that usually follow a heterologous transfusion. Both immediate after transfusion recovery and survival of
51
Cr-labeled sickle erythrocytes were decreased in comparison to the values obtained for control erythrocytes from individuals without sickle-cell anemia. Survival of sickle erythrocytes was improved during exposure of the animals to 100% O
2
. Hypoxia (7-10% O
2
) resulted in the abrupt removal of 35-60% of sickle erythrocytes from the rats' circulation. Variations in oxygen tension did not affect survival of control erythrocytes. The usefulness of this convenient animal model for the study of sickle-cell anemia is suggested by the similarities between our results and the behavior of sickle erythrocytes in humans. The system may also be suitable for studying a wide variety of other human erythrocyte disorders.
Messenger Selection by Bacterial Ribosomes
Authors: Leffler S. , Szer W.
Published: May 2006

The counterpart of
Escherichia coli
initiation factor 3(IF-3) was isolated from
Caulobacter crescentus
, purified to homogeneity, and used in comparative studies on
in vitro
translation of RNA from the
C. crescentus
RNA phage Cb5 and of coliphage MS2 RNA. The two phage RNAs are similar in physical properties and analogous in genetic content. The factor, C-IF-3, substitutes for
E. coli
IF-3 and promotes correct translation of MS2 RNA by
E. coli
ribosomes. Conversely,
E. coli
IF-3 substitutes for C-IF-3 in translation of Cb5 RNA by
C. crescentus
ribosomes. However, each phage RNA could be translated only by host ribosomes or by mixed ribosomes containing the host 30S subunit. C-IF-3 dissociates
C. crescentus
and
E. coli
70S ribosomes into subunits. It binds phage, ribosomal, and, less efficiently, transfer RNA.
RNA Polymerases of Maize. Purification and Molecular Structure of DNA-dependent RNA Polymerase II
Authors: Mullinix Kathleen P. , Strain Gustave C. , Bogorad Lawrence
Published: May 2006

Nuclear DNA-dependent RNA polymerase II has been purified from leaves of
Zea mays
by a new procedure that improves enzyme stability and thus permits more manipulation during purification. The purification procedure includes a heating step, gel filtration on Sepharose 6B and 4B, and chromatography on DEAE- and DNA-celluloses. This method of purification yields an enzyme that exhibits maximal activity when denatured DNA is used as a template. Electrophoresis of highly purified enzyme on polyacrylamide gels containing sodium dodecyl sulfate indicates that maize RNA polymerase IIa is composed of several polypeptide subunits. The most highly purified preparations contain polypeptides with molecular weights of 200,000, 160,000, 35,000, 25,000, 20,000, and 17,000.
Binding of Nerve Growth Factor Receptor in Sympathetic Ganglia
Authors: Banerjee Shailesh P. , Snyder Solomon H. , Cuatrecasas Pedro , Greene Lloyd A.
Published: May 2006

125
I-Labeled nerve growth factor binds to membrane preparations from superior cervical ganglia of rabbit in a specific fashion indicative of an interaction with the physiological receptor. Of various tissues examined, binding was observed only in the superior cervical ganglia, a presumed target organ of nerve growth factor. Binding of labeled factor is displaced by nonradioactive factor but not by several other peptide hormones. Binding to ganglia of preparations of nerve growth factor treated with
N
-bromosuccinimide closely parallels their biological activity. Binding of nerve growth factor receptor is saturable with an affinity constant of about 0.2 nM, similar to the reported plasma levels of the factor. Nerve growth factor does not elicit insulin-like biological effects in isolated adipocytes, and it does not modify the binding of [
125
I]insulin or [
125
I]epidermal growth factor to fat cells or liver membranes.
An Immobilized Three-Enzyme System: A Model for Microenvironmental Compartmentation in Mitochondria
Authors: Srere Paul A. , Mattiasson Bo , Mosbach Klaus
Published: May 2006

An immobilized three-enzyme system, malate dehydrogenase (EC 1.1.1.37)-citrate synthase (EC 4.1.3.7)-lactate dehydrogenase (EC 1.1.1.27), was investigated as a model for the rate of oxalacetate production and utilization in mitochondria. Lactate dehydrogenase is included to mimic the NADH-utilizing system of mitochondria. This three-enzyme system was immobilized in three different ways (
1
) on Sephadex G-50 (surface coupling), (
2
) on Sepharose 4B (internal-external coupling), and (
3
) entrapped in polycrylamide gel. The rate of citrate production from malate, NAD
+
, and acetyl CoA was determined continuously in a flow system. Up to about 100% rate enhancements were observed when the immobilized system was compared to identical systems of free enzyme. An even more pronounced increase of rate of up to about 400% compared to the soluble system was measured after addition of pyruvate (to reoxidize formed NADH). These results are interpreted in relation to microenvironmental changes of oxalacetate production and the possible organization of enzymes of the Krebs cycle.
Separation of the Messenger RNAs of Newcastle Disease Virus by Gel Electrophoresis
Authors: Collins Bonnie Spanier , Bratt Michael A.
Published: May 2006

We have separated the 18-22S putative messenger RNA of Newcastle disease virus into seven species ranging in molecular weight from 0.55 to 1.53 × 10
6
using sodium dodecyl sulfate-acrylamide-gel electrophoresis at relatively high concentrations of acrylamide and for a relatively long time. Studies of the number and molecular weights of the proteins and the 18-22S RNAs of the virus suggests that these RNAs are in the right molecular weight range to code for the known proteins of Newcastle disease virus. In preliminary studies using this separation technique, we have demonstrated that: (
a
) there is no difference between the 18-22S RNA made during a normal infection and when genome replication is blocked; and (
b
) there is a strain-specific difference between the RNAs of Newcastle disease virus-AV and Newcastle disease virus-HP.
Resonance Raman Studies of the Electronic State of Oxygen in Hemerythrin
Authors: Dunn John B. R. , Shriver Duward F. , Klotz Irving M.
Published: May 2006

Excitation of oxyhemerythrin with radiation within the envelope of its strong oxygen → iron chargetransfer band generates two Raman frequencies, at 844 cm
-1
and 500 cm
-1
. These are assigned to O-O and Fe-O stretching modes. Confirmation of these assignments is provided by the observed shifts in frequency when
16
O
2
is substituted by
18
O
2
as ligand. Comparison of the position of the 844-cm
-1
band with band positions of small molecules of known oxidation state clearly establishes that the bound oxygen is in an O
2
2-
, peroxide-type, electronic state.
Pyridoxal Compounds as Specific Reagents for the α and β N-Termini of Hemoglobin
Authors: Benesch Ruth E. , Yung Suzanna , Suzuki Tomokazu , Bauer Christian , Benesch Reinhold
Published: May 2006

Bifunctional pyridoxal derivatives with a charged side chain in the 5′ position react specifically with the N-terminal valine residues of hemoglobin. Three of these compounds, which have only a single negative charge in the side chain, are highly selective for the α-chain N-terminal residues in the oxy conformation while pyridoxal phosphate, with two negative charges, reacts specifically with the β N-terminal in deoxyhemoglobin. Schiff's base formation, therefore, results in decreased oxygen affinity with pyridoxal phosphate but increased oxygen affinity with the other three compounds. Reduction with sodium borohydride leads to irreversible coupling at either end of the molecule, and preparation and properties of such derivatives are described.
Cell-Free Translation of Maternal Messenger RNA from Sea Urchin Eggs
Authors: Gross K. W. , Jacobs-Lorena M. , Baglioni C. , Gross P. R.
Published: May 2006

The template activity of RNA extracted from unfertilized sea urchin eggs was demonstrated in a cell-free translation system, and, for the first time, specific proteins were identified among the products. All messenger RNA activity is recovered, under the conditions used, from the postribosomal supernatant. Histones, among many other proteins, were identified specifically as products of this “maternal” messenger RNA.
Cell Interactions Between Histoincompatible T and B Lymphocytes. The H-2 Gene Complex Determines Successful Physiologic Lymphocyte Interactions
Authors: Katz David H. , Hamaoka Toshiyuki , Dorf Martin E. , Benacerraf Baruj
Published: May 2006

We used congenic-resistant mouse strains to answer questions concerning the respective roles of genes coding for major histocompatibility and background genotypes in T (thymus-derived)-B (bone marrow-derived) lymphocyte cooperative responses to hapten-protein conjugates. These studies demonstrate conclusively that the gene or genes present in the H-2 complex control the capacity of antigen-specific T and B cells to effectively interact. These findings led us to postulate that there exists on the B-lymphocyte surface an “acceptor” molecule for the active T-cell product or for the T cell itself.
Setae of the First Antennae of the Copepod
Cyclops scutifer
(Sars): Their Structure and Importance
Authors: Strickler J. Rudi , Bal Arya K.
Published: May 2006

Ultrastructural studies of the setae of the first antennae of
Cyclops scutifer
(Sars) have revealed their sensory function. The setae are the extension of modified ciliary structures which function as mechanoreceptors. The setae apparently act to detect gravitational and inertial forces. This is of particular importance in sensing disturbances generated by prey or predators.
Stimulation of Polypeptide Initiation
In Vitro
After Protein Synthesis Inhibition
In Vivo
in HeLa Cells
Authors: Reichman Marsha , Penman Sheldon
Published: May 2006

Crude cytoplasmic extracts prepared from HeLa cells actively incorporate amino acids but show little initiation of new peptides (as seen by labeling of N-terminal amino acids). In contrast, extracts prepared from cells subjected to prior inhibition of protein synthesis show a significant amount of polypeptide initiation indicated by formation of peptides with radioactive N-terminal methionine. The same result was obtained whether prior inhibition occurred with cycloheximide or by starvation for an essential amino acid. Cellular response to suppression of protein synthesis appears to be mediated through production of RNA, since it is inhibited by actinomycin but appears in the presence of cycloheximide. The crude extracts continue initiating new polypeptides for at least 10 min
in vitro
. It is postulated that enhancement of
in vitro
initiation described here is related to the apparent stimulation of initiation of translation seen
in vivo
.
Effects of 5-Hydroxykynurenamine, a New Serotonin Metabolite, on Isolated Dog Basilar Arteries
Authors: Toda Noboru , Tokuyama Takashi , Senoh Siro , Hirata Fusao , Hayaishi Osamu
Published: May 2006

Serotonin and 5-hydroxykynurenamine caused dose-related contractions in the spiral strips of dog basilar arteries. The potency of 5-hydroxykynurenamine was approximately 1/100 that of serotonin, the former frequently causing a transient relaxation preceding the contraction. The contractile responses to 5-hydroxykynurenamine and serotonin were attenuated by methysergide. Treatment with 5-hydroxykynurenamine inhibited the response to serotonin, and this inhibitory effect was not completely reversed by removal of 5-hydroxykynurenamine from the bathing medium. The contractile response to K
+
was only slightly attenuated by high concentrations of 5-hydroxykynurenamine. It appears that 5-hydroxykynurenamine and serotonin share receptors in dog basilar arteries and that the effect of serotonin is specifically antagonized by 5-hydroxykynurenamine.
Asymmetry in the 50S Ribosomal Subunit of
Escherichia coli
Authors: Moore P. B. , Engelman D. M. , Schoenborn B. P.
Published: May 2006

A substantial separation of the centers of mass of the protein and RNA portions of the 50S ribosomal subunit has been achieved using neutron scattering. This separation reveals that the subunit has a protein-rich side, a finding which is inconsistent with many models proposed for the structure. By analyzing the variation of the radius of gyration of the subunit under conditions in which the contributions of the protein and RNA were separately enhanced by deuteration and comparing these radii to the undeuterated subunit radius, we have obtained the following values. The radius of gyration of the whole particle is 78.0 ± 0.95 Å, that of the RNA moiety is 72.5 ± 1.5 Å, and that of the protein is 73.4 ± 2.0 Å. These data give a separation of the centers of mass of the RNA and protein distributions of 57.7 ± 10 Å.
Collagen Biosynthesis in Nonfibroblastic Cell Lines
Authors: Langness Uwe , Undenfriend Sidney
Published: May 2006

Prolyl hydroxylase and other enzymes of collagen synthesis have been found in cloned cells, including epithelium, melanoma, liver, HeLa, pituitary, kidney, and neuroblastoma. The significance of collagen biosynthesis in nonfibroblastic cells lines is discussed.
ACTH Antagonists
Authors: Hofmann Klaus , Montibeller Judith A. , Finn Frances M.
Published: May 2006

Structural modifications within the active site of the ACTH molecule have produced analogs that inhibit the hormone sensitive adenylate cyclase system of bovine adrenal cortical plasma membranes. It is demonstrated that the tryptophan residue of the ACTH molecule is essential for stimulation of the enzyme. Substitution of tryptophan by phenylalanine or by
N
α
-methyltryptophan as in [Gln
5
, Phe
9
]corticotropin
1-20
amide or [
N
α
-Metrp
9
]corticotropin
1-24
provides ACTH analogs that exhibit high affinity for the ACTH receptor(s) but fail to activate the adenylate cyclase system. It is concluded that affinity for the receptors alone is not sufficient for expression of hormonal activity. The observation that adrenal cortical adenylate cyclase activated by fluoride ion is not inhibited by the antagonists indicates that hormonal and fluoride activation proceed via different mechanisms.
Insulin-Dependent Regulation of Insulin Receptor Concentrations: A Direct Demonstration in Cell Culture
Authors: Gavin James R. , Roth Jesse , Neville David M. , De Meyts Pierre , Buell Donald N.
Published: May 2006

Chronic (5-16 hr) exposure of cultured human lymphocytes to 10
-8
M insulin at 37°
in vitro
produced a decrease in insulin receptor concentrations unaccounted for by simple occupancy of sites; acute exposure (0-2 hr) was without effect. These results reproduced observations
in vivo
where chronic hyperinsulinemia (e.g., 10
-8
M insulin in the circulation of obese insulinresistant hyperglycemic mice) is associated with a substantial reduction in the concentration of insulin receptors per cell, while acute hyperinsulinemia
in vivo
has no effect on receptor concentration. These data suggest a reciprocal relationship between insulin in the extracellular fluid and the concentration of insulin receptors per cell, which is mediated at the target cell itself by intracellular insulin-sensitive regulatory processes and directly affects target-cell sensitivity to hormone.
The Requirement for Ribosomal Proteins L7 and L12 in Peptide-Chain Termination
Authors: Brot Nathan , Tate W. P. , Caskey C. T. , Weissbach Herbert
Published: May 2006

Proteins L7 and L12 from 50S ribosomal subunits of
Escherichia coli
are required for peptidechain termination. This termination process is inhibited by thiostrepton. Since both thiostrepton-treated ribosomes and those depleted of L7 and L12 have a markedly reduced ability to form release factor·UA[
3
H]A·ribosome complexes, the binding of release factors to the ribosome appears to be the primary site of inhibition.
Identification of Methylated Nucleosides in Messenger RNA from Novikoff Hepatoma Cells
Authors: Desrosiers Ronald , Friderici Karen , Rottman Fritz
Published: May 2006

The poly(A) tract found in eukaryotic mRNA was used to study methylation in mRNA obtained from Novikoff hepatoma cells. Methyl labeling of RNA was achieved with L-[
methyl
-
3
H]methionine under conditions that suppress radioactive incorporation into the purine ring. RNA that contains a poly(A) segment was obtained from polysomal RNA by chromatography on oligo(dT)-cellulose. Sucrose density gradient centrifugation of this RNA revealed a pattern expected for mRNA. The composition of the methyl-labeled nucleosides in the RNA was analyzed after complete enzymatic degradation to nucleosides. By use of DEAE-cellulose (borate) chromatography, which separates 2′-
O
-methylnucleosides from normal and base-methylated nucleosides, about 50% of the radioactivity was recovered in the 2′-
O
-methylnucleoside fraction and 50% in the base-methylnucleoside fraction. High-speed liquid chromatography (Aminex A-5) of the 2′-
O
-methylnucleoside fraction produced four peaks coincident with the four 2′-
O
-methylnucleoside standards. Analysis of the base-methylnucleoside fraction revealed a unique pattern. While ribosomal RNA and tRNA possessed complex base-methylnucleoside patterns, the distribution in mRNA was quite simple, consisting predominantly of
N
6
-methyladenosine. These results demonstrate a unique distribution of methylated nucleosides in mRNA. By analogy to ribosomal RNA synthesis, the presence of methylnucleosides in mRNA may reflect a cellular mechanism for the selective processing of certain mRNA sequences.
Location of the Spike Glycoproteins in the Semliki Forest Virus Membrane
Authors: Garoff Henrik , Simons Kai
Published: May 2006

Labeling experiments with formyl-[
35
S]-methionyl sulfone methylphosphate and crosslinking studies with dimethylsuberimidate suggest that the spike glycoproteins of Semliki Forest virus extend through the viral membrane into close contact with the nucleocapsid. Based on this finding, we present a mechanism for the formation of virus-specific patches in the host cell plasma membrane during virus assembly.
Initiation of Oncogenic Transformation of Mouse Lymphocytes
In Vitro
by Abelson Leukemia Virus
Authors: Sklar Marshall D. , White Beverly J. , Rowe Wallace P.
Published: May 2006

While C-type RNA viruses are known to induce leukemias and lymphomas, oncogenic transformation of lymphoid cells by them
in vitro
has not been reported. In this study, splenocytes from female BALB/c mice were infected
in vitro
with Abelson virus, a C-type RNA virus that induces nonthymic lymphomas and plasmacytomas in mice. The cells were transplanted into recipients of different karyotype, either male BALB/c mice or hybrid BALB/c × AL/N (CALF1) mice, which bear the
Rb(5.19)
1
Wh
translocation. Transplants of eight of the resulting tumors (one plasmacytoma and seven lymphomas) contained cells of donor BALB/c karyotype, indicating that transformation of splenocytes occurred
in vitro
.
Elongation of the Polyadenylate Segment of Messenger RNA in the Cytoplasm of Mammalian Cells
Authors: Diez J. , Brawerman G.
Published: May 2006

Chinese hamster and mouse sarcoma 180 ascites cells, treated with high levels of actinomycin D, still carry out limited poly(A) synthesis. The residual activity, which consists of poly(A) chain extension in the cytoplasm as well as in the nucleus, is essentially insensitive to cordycepin. Nuclear polyadenylation proceeds linearly and involves the gradual extension of unusually long poly(A) sequences. Cytoplasmic poly(A) labeling is initially more rapid than in the nucleus, but levels off within 5-10 min. It consists of addition of seven to eight AMP residues to the poly(A) sequences in preexisting mRNA molecules. The levelling off can be accounted for by a rapid turnover of the extremity of the poly(A) chain in the mRNA. Cytoplasmic poly(A) chain extension can be detected in cells not subjected to the actinomycin treatment. The rate of this process is of the same order of magnitude as that of new poly(A) transfer from nucleus to cytoplasm. It could serve to control the length of the poly(A) sequence in mRNA.
Specific Sites of Interaction Between Histones and DNA in Chromatin
Authors: Axel R. , Melchoir W. , Sollner-Webb B. , Felsenfeld G.
Published: May 2006

Staphylococcal nuclease digestion of purified chromatin from duck reticulocytes or calf thymus results in the production of a series of double-stranded DNA fragments of discrete molecular size, ranging from about 130 to 45 base pairs, which can be detected by polyacrylamide gel electrophoresis. Similar patterns of protected DNA fragments are obtained from limit digests of chromatin “reconstituted” from purified DNA and chromatin proteins. The results obtained with reconstituted material do not depend upon the origin of the DNA, which may be derived from a bacterial, viral, or homologous source. The specificity of the protective mechanism, therefore, resides in the structure of the bound histones, and probably not in any special nucleotide sequences present in the DNA. Removal of lysine-rich histones from chromatin before digestion results principally in disappearance from the digest of a DNA fragment about 130 base pairs long. Our preliminary results suggest that other elements of the digest pattern can be assigned uniquely to the remaining histone components. These results indicate that the binding of histones to DNA in chromatin involves a limited number of specific and very well defined contacts between protein and nucleic acid, which arise from structural properties of the histones.
Alterations in Glucose Metabolism in Chick-Embryo Cells Transformed by Rous Sarcoma Virus: Intracellular Levels of Glycolytic Intermediates
Authors: Singh Vishwa Nath , Singh Malathy , August J. T. , Horecker B. L.
Published: May 2006

Chick-embryo cells, transformed with Rous sarcoma virus, show enhanced rates of sugar transport and glycolysis. Determination of intracellular concentrations of glycolytic intermediates suggests that the enhanced glycolytic flux is due to increased activities of hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1), phosphofructokinase, (ATP:D-fructose-1-phosphate 6-phosphotransferase, EC 2.7.1.56), and pyruvate kinase (ATP:pyruvate 2-
O
-phosphotransferase, EC 2.7.1.40), and not directly to the increased glucose transport. This conclusion is supported by the finding that the intracellular concentration of free glucose is decreased, rather than increased, in the transformed cells. The present observations suggest that the increased glycolytic flux is related to an increased rate of phosphorylation of glucose, and that hexokinase in the transformed cells is at least partly released from its normal control mechanism involving feedback inhibition by glucose-6-
P
.
Further Comparison of Predicted and Experimentally Determined Structure of Adenylate Kinase
Authors: Kabat Elvin A. , Wu Tai Te
Published: May 2006

An analysis is made of various predictive methods used to locate α-helices and β-sheets in proteins. The analysis is based on attempts to locate the α-helices and β-sheets in adenylate kinase (ATP:AMP phosphotransferase EC 2.7.4.3) from the sequence without prior knowledge of the x-ray findings. Specification of the β-sheet breaking and α-helix breaking tripeptides, a method independent of the others combined with the best of the other methods would substantially reduce the prediction of nonexistent β-sheets and to a lesser extent would aid in locating α-helices.