Activity of partially purified protein chain initiation factors from the livers of dimethylnitrosamine-treated rats.
Partially purified polypeptide chain initiation factors were prepared from the 0.5 M KCl wash of rat liver microsomes. Their activities in connection with dimethylnitrosamine (DMNA)-induced inhibition of protein synthesis were studied by use of the following reactions: (1) poly(U)-directed binding of Phe-tRNA to ribosomes, (2) formation of a GTP-dependent ternary initiation complex with Met-tRNAf, (3) binding of Met-tRNAf to 40-S ribosomal subunits, (4) assembly of a Met-tRNAf containing 80-S ribosomal initiation complex and (5) ribosome-dependent GTPase activity. The inhibition of protein synthesis with DMNA was not associated with a loss of factor activity in any of these reactions. In the binding of Met-tRNAf to 40-S subunits there was a noticeable increase, probably related to the stability of the resulting complex. The Met-tRNA deacylase activity was also increased.
D000818:Animals; D004128:Dimethylnitrosamine / Q000494:pharmacology*; D004950:Esterases / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008715:Methionine; D009602:Nitrosamines / Q000494:pharmacology*; D010448:Peptide Initiation Factors / Q000378:metabolism*; D012343:RNA, Transfer / Q000302:isolation & purification; D051381:Rats; D012270:Ribosomes / Q000032:analysis
D009602:Nitrosamines; D010448:Peptide Initiation Factors; D012343:RNA, Transfer; D008715:Methionine; D004950:Esterases; D020558:GTP Phosphohydrolases; D004128:Dimethylnitrosamine