Differences in the structure of A and B forms of human monoamine oxidase.
[3H]Pargyline-labeled polypeptides associated with the A and B types of monoamine oxidase (MAO) activity in human tissues were analyzed by sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE). [3H]Pargyline was bound to MAO A in a crude mitochondrial fraction from the placental trophoblast of a male newborn and to MAO B in blood platelets from the umbilical vein of the same newborn. [3H]Pargyline was also bound to MAO A and B in a crude mitochondrial fraction from cultured skin fibroblasts of a male adult and to MAO B in blood platelets from the same individual. Specific labeling of proteins associated with type A or type B activity in fibroblast cells was achieved by preincubation with selective B or A inhibitors, respectively. For all tissues, SDS-PAGE of [3H]pargyline-bound samples revealed a labeled protein band of apparent molecular weight 63,000 for MAO A and 60,000 for MAO B. When SDS-solubilized, [3H]pargyline-labeled MAO A and B proteins from the same male newborn 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 distinct enzyme molecules are associated with the A and B types of human MAO activity.
D000328:Adult; D001665:Binding Sites; D001792:Blood Platelets / Q000201:enzymology; D002460:Cell Line; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008970:Molecular Weight; D008995:Monoamine Oxidase / Q000378:metabolism*; D010293:Pargyline / Q000378:metabolism*; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D011485:Protein Binding; D012867:Skin; D014327:Trophoblasts / Q000201:enzymology
D010293:Pargyline; D008995:Monoamine Oxidase