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Differences in the Structure of A and B Forms of Human Monoamine Oxidase
Author(s) -
Cawthon Richard M.,
Pintar John E.,
Haseltine Florence P.,
Breakefield Xandra O.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb00464.x
Subject(s) - monoamine oxidase , monoamine oxidase b , monoamine neurotransmitter , neuroscience , chemistry , psychology , biochemistry , serotonin , enzyme , receptor
[ 3 H]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). [ 3 H]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. [ 3 H]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 [ 3 H]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, [ 3 H]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 [ 3 H]pargyline‐labeled peptides were obtained. These findings indicate that distinct enzyme molecules are associated with the A and B types of human MAO activity.