40S subunit X Met-tRNAf complexes and initiation factor eIF-2 phosphorylation in mammalian cells accumulating uncharged tRNA.
A significant, reversible decline in the level of 40S subunit X Met-tRNAf complexes was observed in HeLa cells treated with either of two inhibitors of tRNA charging, histidinol or O-methylthreonine. A decline in 40S X subunit Met-tRNAf complexes was also seen in HeLa cells deprived of histidine and in mutant Chinese hamster ovary cells, bearing a temperature-sensitive leucyl-tRNA charging enzyme, when they were incubated at a non-permissive temperature. Treatment with histidinol or O-methylthreonine did not affect the relative degree of phosphorylation of the alpha subunit of initiation factor eIF-2. Histidinol did not stimulate the activity of the endogenous kinase for eIF-2 alpha subunit in extracts prepared from HeLa cells. In the presence of histidinol the phosphorylation level of a 25000-dalton protein was reversibly increased.
D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D006367:HeLa Cells; D006641:Histidinol / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D010448:Peptide Initiation Factors / Q000378:metabolism*; D010766:Phosphorylation; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000378:metabolism; D012343:RNA, Transfer / Q000302:isolation & purification* / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D012358:RNA, Transfer, Met; D011817:Rabbits; D019892:eIF-2 Kinase
D010448:Peptide Initiation Factors; D012346:RNA, Transfer, Amino Acyl; D012358:RNA, Transfer, Met; C024988:tRNA, formylmethionine-; D006641:Histidinol; D012343:RNA, Transfer; D011494:Protein Kinases; D019892:eIF-2 Kinase