Molecular cloning, chromosomal mapping, and characterization of the mouse UDP-galactose:ceramide...

UDP-galactose:ceramide galactosyltransferase (CGT) (EC 2.4.1.62) catalyzes the final step in the synthesis of galactocerebroside, a glycosphingolipid characteristically abundant in myelin. In this report, we describe the isolation of genomic clones spanning the mouse CGT gene. The mouse CGT gene consists of six exons that span a minimum of 70 kb of DNA and that encode a 541 amino acid translation product with extensive sequence similarity to the rat CGT enzyme and to UDP-glucuronosyltransferases (UGT). The 5'-untranslated region of the mouse CGT gene is encoded by a separate exon located approximately 25 kb upstream of the first protein-encoding exon. Furthermore, the genomic organization of the five coding region exons of the mouse CGT gene resembles that of the human UGT1 and rat UGT2B1 genes. Finally, analysis of somatic cell hybrids by PCR and fluorescence in situ hybridization to metaphase chromosomes has localized the mouse CGT gene to chromosome 3, bands E3-F1.