title: Effect of nucleoside 5'-triphosphates on tRNA nucleotidyltransferase activity in cytoplasmic fractions of various types of mammalian cells.
abstract: The tRNA nucleotidyltransferase activity (3H-CMP incorporation into 3'-terminus of tRNApC) in cytoplasmic fractions of various types of cells such as Ehrlich ascites tumor cells, mouse liver and spleen cells, rat spleen, lymph node, and macrophages cells was found to be dependent on the concentrations of nucleoside 5'-triphosphates (ATP, GTP, UTP, dATP, dGTP, dCTP, and/or dTTP). The purified tRNA nucleotidyltransferase did not show such dependency. The dependency of the enzyme activity on nucleoside 5'triphosphates in the crude cytoplasmic fractions was possibly due to the presence of inhibitors which interfere with the repair system of defective 3'-termini of tRNA. Two kinds of inhibitors were distinguishable in the cytoplasmic fractions. One was unstable on heat treatment at 55 decrees C and showed ribonuclease activity for the tRNA 3'-terminus. The other which lacked ribonuclease activity was rather stable to the heat treatment and inhibited purified tRNA nucleotidyltransferase. The actions of both inhibitors were suppressed by nucleoside 5'-triphosphates.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology*; D003854:Deoxyribonucleotides / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D008099:Liver / Q000201:enzymology; D008198:Lymph Nodes / Q000201:enzymology; D008264:Macrophages / Q000201:enzymology; D008297:Male; D051379:Mice; D009711:Nucleotides / Q000494:pharmacology*; D012316:RNA Nucleotidyltransferases / Q000378:metabolism*; D012343:RNA, Transfer; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism; D013154:Spleen / Q000201:enzymology; D013696:Temperature
chemical_list: D003854:Deoxyribonucleotides; D009711:Nucleotides; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D012316:RNA Nucleotidyltransferases; D012260:Ribonucleases