title: Non-linear kinetics of glutamyl-tRNA synthesis catalyzed by high molecular weight complexes from rat brain neuronal cells but not from glial cells.
abstract: High molecular weight complexes of aminoacyl-tRNA synthetases isolated from rat brain catalyze the formation of glutamyl-tRNA with an initial lag time of the order of 1 min, as previously reported for the formation of glutamyl-tRNA and glutaminyl-tRNA catalyzed by similar complexes from bovine brain (Vadeboncoeur and Lapointe, Eur. J. Biochem., 109 (1980) 581-587). To determine the type(s) of brain cell(s) where this phenomenon occurs, we have studied the kinetics of glutamyl-tRNA formation catalyzed by high molecular weight complexes of aminoacyl-tRNA synthetases isolated from neuronal and from glial cells, either transformed (Neuro-2A and C6), or from primary cultures, or isolated from rat brain. The delay in the formation of glutamyl-tRNA was observed only in the case of neuronal cells isolated from rat brain, whereas a delay in the formation of glutaminyl-tRNA was also seen in these cells, as well as in neuronal cells in primary culture and in synaptosomes. The kinetics of formation of aspartyl-tRNA and valyl-tRNA catalyzed by high molecular weight complexes from all these cells was linear.
mesh_terms: D000215:Acylation; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002384:Catalysis; D002460:Cell Line; D005910:Glioma / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D005973:Glutamine / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D009447:Neuroblastoma / Q000378:metabolism; D009457:Neuroglia / Q000201:enzymology / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000096:biosynthesis* / Q000378:metabolism; D051381:Rats; D013379:Substrate Specificity; D014633:Valine / Q000378:metabolism
chemical_list: D005971:Glutamates; D046911:Macromolecular Substances; D012346:RNA, Transfer, Amino Acyl; D005973:Glutamine; D001224:Aspartic Acid; D018698:Glutamic Acid; D000604:Amino Acyl-tRNA Synthetases; D014633:Valine