title: Partial digestion of tRNA--aminoacyl-tRNA synthetase complexes with cobra venom ribonuclease.
abstract: Transfer RNA molecules have been labeled with 32P at the 5' or 3' end and digested with cobra venom ribonuclease, which preferentially cuts double-stranded regions. The products of yeast tRNAPhe and tRNAVal were analyzed by high-resolution gel electrohporesis. In the free state, these tRNAs were cut predominantly in the acceptor and anticodon stems. Minor cuts occurred in the T psi stem in tRNAVal. The topography of zones interacting with their cognate synthetases was studied by determining the tRNA regions shielded by protein. Nearly 100% protection was found in the anticodon and acceptor stem of tRNAVal, while in tRNAPhe only the stem of the anticodon was protected. Noncognate interactions between tRNAPhe and tryptophanyl-tRNA synthetase from beef pancreas were examined. The beef enzyme did not protect tRNAPhe despite the fact that efficient misaminoacylation occurred. The pattern of shielding obtained for each tRNA-synthetase complex was compared with the results of direct ultraviolet cross-linking experiments with these complexes.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D004546:Elapid Venoms; D046911:Macromolecular Substances; D010652:Phenylalanine-tRNA Ligase / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D014637:Valine-tRNA Ligase / Q000378:metabolism
chemical_list: D004546:Elapid Venoms; D046911:Macromolecular Substances; D012343:RNA, Transfer; D012260:Ribonucleases; D000604:Amino Acyl-tRNA Synthetases; D010652:Phenylalanine-tRNA Ligase; D014637:Valine-tRNA Ligase