title: The beta subunit of E. coli glycyl-tRNA synthetase plays a major role in tRNA recognition.
abstract: The contributions made by the alpha and beta subunits of E. coli glycyl-tRNA synthetase to the recognition of tRNA have been investigated via binding and immunological methods. Using the nitrocellulose filter assay, we have shown that isolated beta subunit, but not the alpha subunit, binds [14C]glycyl-tRNA with an affinity comparable to that of the native enzyme. Further, the data indicate that the beta subunit possesses one binding site for glycyl-tRNA while the native or reconstituted enzyme (alpha 2 beta 2) has two sites. Rabbit antibodies directed at the beta subunit or the holoenzyme inhibit efficiently the ability of the enzyme to aminoacylate tRNA while alpha-subunit antibodies have a smaller effect. Since none of the antisera have an appreciable effect on the ATP-PPi exchange activity of the enzyme under these conditions, the beta-subunit (and holoenzyme) antisera evidently interfere with productive tRNA binding. Taken together, the data indicate that the larger, beta subunit of glycyl-tRNA synthetase plays a major role in tRNA recognition.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D000936:Antigen-Antibody Complex; D004926:Escherichia coli / Q000235:genetics*; D006032:Glycine-tRNA Ligase / Q000378:metabolism*; D007106:Immune Sera; D007700:Kinetics; D046911:Macromolecular Substances; D011485:Protein Binding; D012343:RNA, Transfer / Q000235:genetics* / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics* / Q000378:metabolism
chemical_list: D000936:Antigen-Antibody Complex; D007106:Immune Sera; D046911:Macromolecular Substances; D012346:RNA, Transfer, Amino Acyl; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; D006032:Glycine-tRNA Ligase