Characterization of alpha-galactosidase isoenzymes in normal and Fabry human-Chinese Hamster somatic cell hybrids

The alpha-galactosidases in normal man-Chinese hamster somatic cell hybrids were investigation with antibodies specific for human alpha-galactosidase A and antibodies specific for Chinese hamster alpha-galactosidase. It was found that an isoenzyme in hybrid cells, which has an electrophoretic mobility between that of human alpha-galactosidase A and Chinese hamster alpha-galactosidase, contains immunologic determinants of both human and Chinese hamster origin, suggesting that it is a heteropolymeric molecule. Moreover, the locus for human alpha-galactosidase, which was found to be X-linked, is the locus coding for alpha-galactosidase A. Hybrids isolated after fusion of Chinese hamster cells with cells of a patient with Fabry's disease did not express human alpha-galactosidase A or the heteropolymeric molecule even in the presence of the active human X chromosome, indicating that the deficiency of alpha-galactosidase A in Fabry's disease is probably due to a mutation in a structural gene resulting in the inability to form immunologically detectable and functionally active molecules of alpha-galactosidase A.