Differences in the structures of monoamine oxidases A and B in rat clonal cell lines.
[3H]Pargyline-labeled polypeptides associated with the A and B types of monoamine oxidase (MAO) activity in two rat cell lines were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). [3H]Pargyline was bound to MAO A and B in a crude mitochondrial fraction from rat hepatoma cell line MH1C1 and to MAO A in a mitochondrial fraction from rat glioma line C6. Specific radiolabeling of proteins associated with type A or B activity in the hepatoma samples was achieved by incubation with selective B or A inhibitors, respectively, prior to [3H]pargyline binding. Following [3H]pargyline binding, the samples were solubilized by heating in sodium dodecyl sulfate (SDS) in the presence of a reducing agent. SDS-PAGE of [3H]pargyline bound samples revealed a radiolabeled protein band of apparent molecular weight (mol. wt) 63,000 daltons associated exclusively with MAO A activity and a band of apparent mol. wt 60,000 associated exclusively with MAO B activity. Furthermore, when SDS-solubilized, [3H]pargyline-labeled MAO A and B proteins from these cell lines were subjected to limited proteolysis and one-dimensional peptide mapping in SDS gels, different patterns of [3H]pargyline-labeled peptides were obtained. These findings indicate that the A and B forms of MAO activity are associated with enzyme molecules of different primary covalent structures determined by different gene loci.
D000818:Animals; D002460:Cell Line; D055598:Chemical Phenomena; D002621:Chemistry; D002999:Clone Cells / Q000201:enzymology; D006868:Hydrolysis; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D008995:Monoamine Oxidase / Q000145:classification*; D010293:Pargyline / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D051381:Rats
D010446:Peptide Fragments; D010293:Pargyline; D008995:Monoamine Oxidase