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E M Scolnick

Publications and source records attributed to E M Scolnick.

195 records · Page 11Linked to original sources
PubMed1971

Hydrolysis of fMet-tRNA by peptidyl transferase.

Escherichia coli and rabbit reticulocyte (f[(3)H]Met-tRNA.AUG.ribosome) intermediates undergo hydrolysis, with release of f[(3)H]methionine, upon addition of tRNA or CpCpA in the presence of acetone. This ribosomal catalyzed reaction has similar requirements, pH optimum, and antibiotic sensitivity to those of peptidyl transferase. Two antibiotics, lincomycin with E. coli ribosomes and anisomycin with reticulocyte ribosomes, inhibit peptide-bond formation and transesterification activities of peptidyl transferase, but stimulate hydrolysis of f[(3)H]Met-tRNA. Earlier studies have suggested peptidyl transferase activity is essential for R factor-dependent hydrolysis of f((3)H)Met-tRNA. These studies indicate that peptidyl transferase has the capacity for f((3)H)Met-tRNA hydrolysis and, therefore, may be responsible for peptidyl-tRNA cleavage during peptide chain termination.

Animals↗
PubMed1971

Antibody to the RNA-dependent DNA polymerase of mammalian C-type RNA tumor viruses.

Sera from rats bearing transplantable tumors induced by murine C-type tumor viruses contain an inhibitor of the activity of the viral RNA-dependent DNA polymerase. The inhibitor is shown to be an immunoglobulin (IgG) directed against the enzyme. Antiserum made in rabbits against partially purified murine leukemia virus polymerase also inhibits the polymerases of other mammalian C-type RNA-containing tumor viruses. Thus, the polymerases from different mammalian tumor viruses are antigenically related.

Animals↗
PubMed1970

Peptide chain termination. VII. The ribosomal and release factor requirements for peptide release.

Release factors participate in release of fMet from fMet-tRNA . AUG . ribosome intermediates upon binding to ribosomes. This release requires R factor and occurs in the absence of terminator codon in reactions containing 20 per cent ethanol. Release occurs only when both 30S and 50S ribosomal subunits are present and when fMet-tRNA is located in the ribosomal P site. Release factor-dependent deacylation of fMet-tRNA is inhibited by sparsomycin, amicetin, lincocin, and chloramphenicol, antibiotics which have little effect on binding of R factor to ribosomes. The possible role of peptidyl transferase in the release reaction is discussed.

Amino Acid Sequence↗
PubMed1970

DNA synthesis by RNA-containing tumor viruses.

Murine leukemia (Rauscher and Moloney strains) and sarcoma (Kirsten strain) virions, as well as the mammary tumor virus of mice, contain an RNA-dependent DNA polymerase. Optimal incorporation of deoxyribonucleoside triphosphates occurs at a critical detergent (Triton X-100) concentration (0.010-0.014%). At higher than optimal detergent concentrations the virion is seen to be disrupted and enzyme activity is lost. The virion, enzymatic activity, and newly synthesized DNA all cosediment in a sucrose gradient. Thus far the enzymatic activity has been found only in RNA viruses that have oncogenic properties.

Centrifugation, Density Gradient↗
PubMed1969

Peptide chain termination. V. The role of release factors in mRNA terminator codon recognition.

The protein release factors, R1 and R2, bind to ribosomes in response to specific terminator codons (R1 to UAA or UAG, R2 to UAA or UGA). In reactions containing ribosomes, the tritiated oligonucleotide UA[(3)H](A)(2) is retained on nitrocellulose filters in response to either R1 or R2, and UA[(3)H]G in response to R1. These results indicate that an R.terminator codon.70S ribosome intermediate occurs during terminator codon recognition and suggest that protein release factors R1 and R2 recognize terminator codons.

Anti-Bacterial Agents↗
PubMedDate not supplied

ras-Related gene sequences identified and isolated from Saccharomyces cerevisiae.

The oncogenes of Harvey and Kirsten murine sarcoma viruses (v-rasH and v-rasK) and their cellular homologues (c-rasH and c-rasK) constitute two members of the ras gene family. Each functional member of the ras gene family encodes a 21,000 molecular weight protein (p21ras). ras genes have been detected in a wide variety of vertebrate species, including Xenopus laevis (R. E. Steele, personal communication), and in Drosophila melanogaster. We report here the detection of ras-related genes in the yeast Saccharomyces cerevisiae, and the isolation of two ras-related molecular clones, c-rassc-1 and c-rassc-2, from the DNA of Saccharomyces. Both c-rassc-1 and c-rassc-2 hybridize specifically to probes prepared from mammalian ras DNA. Sequencing of c-rassc-1 reveals extensive amino acid homology between the protein encoded by c-rassc-1 and the p21 encoded by c-rasH. Our studies suggest that these clones can be used to elucidate the normal cellular functions of ras-related genes in this relatively simple eukaryotic organism.

Amino Acid Sequence↗
PubMedDate not supplied

Yeast and mammalian ras proteins have conserved biochemical properties.

Mammalian ras oncogenes encode polypeptides of relative molecular mass (Mr) 21,000 (p21) which bind GTP and GDP. Oncogenic ras-encoded proteins differ from their normal homologues by an amino acid substitution for Gly 12, Ala 59 or Gln 61. Recently, we and others have observed that normal p21, encoded by the Ha-ras gene, has a GTP hydrolytic activity that is reduced by the oncogenic substitutions Val 12 or Thr 59. The yeast Saccharomyces cerevisiae contains two ras-related genes, RASsc1 and RASsc2, the expression of either of which is sufficient for viability. RASsc1 and RASsc2 encode proteins of 309 (SC1) and 322 (SC2) residues which are 62% homologous to mammalian p21 in their 172-amino acid N-terminal sequences. We report here that the N-terminal domain of SC1 binds GTP and GDP and has a GTP hydrolytic activity that is reduced in the variants SC1[Thr 66] and SC1[Leu 68] which are analogous to oncogenic Ha[Thr 59] and Ha[Leu 61], respectively. These results suggest that yeast and mammalian ras proteins have similar biochemical and possibly biological functions.

Fungal Proteins↗