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Biomedical subjects

M Rabinovitz

Publications and source records attributed to M Rabinovitz.

At least 109 records · Page 6Linked to original sources
PubMed1973

Factor-promoted dissociation of free ribosomes in a rabbit reticulocyte lysate system: inhibition and requirement for an energy source.

A factor that promoted the dissociation of ribosomes into ribosomal subunits in a complete globin-synthesizing system was isolated from rabbit reticulocyte ribosomes. The factor stimulated both globin synthesis and the association of the small ribosomal subunit with polyribosomes. The dissociation of free ribosomes by the factor could be followed as an independent reaction in the presence of a high concentration of cycloheximide, which inhibited translation and the resulting accumulation of runoff subunits. This reaction required an energy source and was inhibited by P-(5'-guanylyl)-methylenebisphosphonate. These data suggest that energy generated by hydrolysis of GTP may be a requirement for the dissociation reaction. Aurintricarboxylic acid inhibited the factor-mediated dissociation of free ribosomes but not the factor-mediated preservation of subunits formed on peptide-chain termination.

Adenosine Triphosphate↗
PubMed1972

Control of globin synthesis in cell-free preparations of reticulocytes by formation of a translational repressor that is inactivated by hemin.

The control of globin synthesis by hemin in cell-free preparations of rabbit reticulocytes is mediated by an inhibitor (translational repressor) of globin chain initiation that is inactivated by hemin. When the ribosome-free supernatant fraction is warmed at 34 degrees without hemin, it quickly acquires the ability to inhibit a fresh cell-free preparation. If the warmed supernatant fraction is further incubated with hemin, its inhibitory activity is lost. This reversible inhibitor, which is observable only during the early period of incubation without hemin, is distinct from an irreversible inhibitor that becomes prevalent during longer incubations. The reversible inhibitor may be an intermediate in the formation of the irreversible inhibitor. The sensitivity of the reversible inhibitor to inactivation by hemin, which permits resumption of globin synthesis in both intact cells and lysates, indicates that the inhibitor is a physiological regulator.

Animals↗
PubMed1971

Methionineless death in Escherichia coli.

Methionine auxotrophs of strains derived from Escherichia coli 15 lose their colony-forming ability when deprived of this amino acid. Late addition of methionine to liquid cultures did not restore plating efficiency but permitted growth of surviving cells. This phenomenon, termed methionineless death (mld), was not observed with methionine auxotrophs of E. coli strains B, W, or K(12), nor was a similar amino acidless death observed with corresponding auxotrophs of E. coli 15 for arginine, tryptophan, proline, isoleucine, and leucine. Mld was not dependent upon the genetic site determining methionine auxotrophy, nor did it affect the decarboxylation of methionine or the stability of methionyl-transfer ribonucleic acid synthetase activity of starved cells. Death was not altered by the presence of spermine or spermidine but was abolished by the methionine analogue, alpha-methylmethionine. Simultaneous starvation of another amino acid in a multiple auxotroph also significantly reduced mld, suggesting a possible role of protein synthesis. The onset of mld is correlated with a lower net increase of deoxyribonucleic acid.

Amino Acyl-tRNA Synthetases↗