Journal of Neuroscience, Vol 1, 166-175, Copyright © 1981 by Society for Neuroscience
Gene for monoamine oxidase type A assigned to the human X chromosome
JE Pintar, J Barbosa, U Francke, CM Castiglione, M Hawkins Jr and XO Breakefield
Inherited variations in monoamine oxidase (MAO) activity are thought to
affect human behavior and expression of disease. The present study has
established the chromosomal location of one of the structural genes coding
for this enzyme. Mapping was carried out by somatic cell hybridization
between normal human skin fibroblasts and mouse neuroblastoma cells.
Selective media for growth of cells with or without hypoxanthine
phosphoribosyltransferase (HPRT) activity were used to obtain hybrid lines
which had retained or lost the human X chromosome, respectively.
Cytogenetic techniques, isozyme analysis, and limited proteolysis and
peptide mapping of [3H]pargyline-labeled MAO were used to characterize
hybrid lines. With one exception, only lines containing the human X
chromosome and human forms of two X-linked enzymes (phosphoglycerate kinase
and glucose-6-phosphate dehydrogenase) expressed the human form of the
flavin polypeptide of type A MAO. The exceptional hybrid line contained a
putative translocation of part of the human X chromosome, since it
expressed human forms of both MAO and phosphoglycerate kinase but neither
the human form of glucose-6- phosphate dehydrogenase nor HPRT activity.
This evidence indicates that the structural gene for the flavin polypeptide
of MAO-A is on the human X chromosome. This represents the first
chromosomal assignment of a human gene coding for an enzyme of
neurotransmitter metabolism. This information will help to elucidate the
structure of MAO and modes of its inheritance in the human population.