title: Role of ribothymidine in mammalian tRNAPhe.
abstract: We have previously reported that mammalian tRNAsPhe from variation tissues contain different amounts of ribothymidine and that a uridine methylase from Escherichia coli can quantitatively convert these tRNAs to species that contain their full complement ofribothymidine at position 23 from the 3' terminus. The role of ribothymidine in mammalian tRNAs has now been investigated by studying the ability of several highly purified mammalian tRNAsPhe, differing only in their ribothymidine content, to support poly(U)-directed poly(Phe) synthesis under various conditions. Our results indicate that the ribothymidine content of mammalian tRNAPhe can be correlated with the ability of these tRNAs to functionin vitro in a low-magnesium (6 mM), ribosome wash factor-dependent, poly(U)-directed poly(Phe) synthesis system from rat liver. Specifically, the effect of increasing the ribothymidine content in a class C mammalian tRNA becomes manifest in an increased apparent maximum velocity for the overall synthesis of poly(Phe), while the apparent Michaelis constant (Km) remains essentially unchanged. It is postulated that the modifiednucleoside ribothymidine might be involved in the regulation of protein synthesis at the level of translation in mammalian liver.
mesh_terms: D000818:Animals; D002417:Cattle; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D010452:Peptide Biosynthesis; D010649:Phenylalanine; D011072:Poly U; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D051381:Rats; D012270:Ribosomes / Q000378:metabolism; D013045:Species Specificity; D014529:Uridine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D012346:RNA, Transfer, Amino Acyl; C009182:ribothymidine; D011072:Poly U; D010649:Phenylalanine; D012343:RNA, Transfer; D014529:Uridine
references.citation: Biochem J. 1961 Aug;80:324-32
references.pmid: 13785321
references.citation: Biochim Biophys Acta. 1977 Mar 18;475(2):383-92
references.pmid: 843534
references.citation: Cancer Res. 1976 Nov;36(11 Pt. 2):4320-9
references.pmid: 987847
references.citation: Cell. 1975 Nov;6(3):407-13
references.pmid: 1052774
references.citation: FEBS Lett. 1974 May 15;42(1):15-7
references.pmid: 4604411
references.citation: FEBS Lett. 1974 Nov 1;48(1):50-2
references.pmid: 4609801
references.citation: Nat New Biol. 1973 Dec 5;246(153):135-8
references.pmid: 4586558
references.citation: Biochem Biophys Res Commun. 1973 Nov 16;55(2):477-83
references.pmid: 4588216
references.citation: Biochemistry. 1973 Oct 9;12(21):4146-54
references.pmid: 4583318
references.citation: Annu Rev Biochem. 1973;42:439-70
references.pmid: 4199854
references.citation: Biochim Biophys Acta. 1973 Aug 10;319(1):25-36
references.pmid: 4582141
references.citation: Nat New Biol. 1972 Jul 19;238(81):72-4
references.pmid: 4558263
references.citation: J Virol. 1974 May;13(5):1134-42
references.pmid: 4132920
references.citation: Cancer Res. 1974 Mar;34(3):643-53
references.pmid: 4359886
references.citation: Arch Biochem Biophys. 1973 Jul;157(1):55-62
references.pmid: 4352057
references.citation: J Biochem. 1970 Mar;67(3):373-87
references.pmid: 4316470
references.citation: Nucleic Acids Res. 1975 Jan;2(1):21-42
references.pmid: 236551
references.citation: Annu Rev Biochem. 1976;45:805-60
references.pmid: 60910
references.citation: FEBS Lett. 1974 Oct 1;47(1):56-9
references.pmid: 4426398
references.citation: Anal Biochem. 1974 May;59(1):263-71
references.pmid: 4407486
references.citation: Biochem Biophys Res Commun. 1972 Feb 25;46(4):1721-7
references.pmid: 5015608
references.citation: J Biol Chem. 1969 Nov 25;244(22):6241-53
references.pmid: 4900513
references.citation: Biochemistry. 1976 Jul 13;15(14):3031-9
references.pmid: 782513
references.citation: Annu Rev Biochem. 1976;45:191-216
references.pmid: 786149
references.citation: J Bacteriol. 1975 Oct;124(1):99-111
references.pmid: 1100618
references.citation: Science. 1975 Nov 7;190(4214):529-35
references.pmid: 1103288
references.citation: Biochim Biophys Acta. 1976 Jul 16;435(4):317-32
references.pmid: 952902
references.citation: Biochem Biophys Res Commun. 1976 Feb 23;68(4):1339-47
references.pmid: 1267781
references.citation: Nature. 1976 May 13;261(5556):159-62
references.pmid: 1272387
references.citation: Biochem Biophys Res Commun. 1975 Oct 27;66(4):1097-105
references.pmid: 1191278
references.citation: Biochemistry. 1975 Nov 18;14(23):5068-73
references.pmid: 1191629
references.citation: J Biol Chem. 1970 Nov 10;245(21):5553-9
references.pmid: 5472357