Accumulation of tRNAMetf on 80-S ribosomes in vitro under the influence of a Met-tRNA deacylase from rat-liver microsomes.
A Met-tRNA deacylase has been partially purified from the 0.5 M KCl wash of rat liver microsomes. In preparative sucrose gradients, the active component sediments as a single band at about 6 S, corresponding to an estimated molecular weight of 1.7 X 10(5). The deacylase is specific for Met-tRNA, without discriminating between Met-tRNA f and Met-tRNAm. Met-tRNAf bound to the initiation factor IF-MP in the ternary complex, IF-MP-GTP-Met-tRNAf, or to initiation-factor-dependent, complexes with 40-S subunits or 80-S ribosomes, is protected against deacylation. However, in the course of the initiation-factor-dependent joining of the 40-S subunit complex to 60-S ribosomal subunits, the bound Met-tRNAf is exposed to added deacylase. Under these conditions, deacylation is inhibited by GTP. The tRNAMetf remains bound and accumulates on the 80-S ribosomes.
D000217:Acyltransferases / Q000302:isolation & purification; D000818:Animals; D001665:Binding Sites; D004950:Esterases / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D007700:Kinetics; D046911:Macromolecular Substances; D008715:Methionine; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors; D012343:RNA, Transfer / Q000378:metabolism*; D051381:Rats; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*
D046911:Macromolecular Substances; D010448:Peptide Initiation Factors; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D008715:Methionine; D000217:Acyltransferases; D004950:Esterases