Assignment of the gene for uridine diphosphate galactose-4-epimerase to human chromosome 1 by human-mouse somatic cell hybridization

Hybrid cell clones between mouse cells deficient in hypoxanthine phosphoribosyltransferase and human diploid cells were analyzed for the expression of human uridine diphosphate galactose-4-epimerase (UDPGal-4-epimerase, EC 5.1.3.2) and for the segregation of human chromosomes. Ten of the 18 independent hybrid clones analyzed were found to express human UDPGal-4-epimerase. Karyotype analysis of these hybrids showed concordant segregation of human UDPGal-4-epimerase with chromosome 1. Human UDPGal-4-epimerase is expressed as a dimeric structure demonstrated by the formation of an intermediate heterodimer migrating between the human and mouse forms in the cell hybrids. The gene specifying this enzyme was also observed to be syntenic with enolase-1. These results indicate that the structural gene for human UDPGal-4-epimerase is located on chromosome 1.