MURINE ALPHA-N-ACETYLGALACTOSAMINIDASE - ISOLATION AND EXPRESSION OF A FULL-LENGTH CDNA AND GENOMIC ORGANIZATION - FURTHER EVIDENCE OF AN ALPHA-GALACTOSIDASE GENE FAMILY

Recent characterization of the human sequences encoding two lysosomal hydrolases, alpha-galactosidase A (alpha-Gal A) and alpha-N-acetylgala ctosaminidase (alpha-GalNAc) revealed that these two enzymes with dist inct enzymatic activities shared about 50% overall amino acid identity and that their genomic sequences had a conserved common gene structur e. These findings suggested that these genes, which are located on dif ferent chromosomes, arose by duplication and divergence from a common ancestral gene. To further compare this alpha-galactosidase gene famil y, the murine alpha-GalNAc cDNA and genomic sequences were isolated an d characterized. The full-length cDNA contained an open-reading frame of 1245 bp encoding a 415 amino acid polypeptide and had 5' and 3' unt ranslated regions of 94 and 333 bp, respectively. The coding region ha d 81% nucleotide and 81.9% amino acid identities with these of the cor responding human alpha-GalNAc sequence. Northern analysis revealed a s ingle transcript of similar to 1.9 kb. The functional integrity of the cDNA was demonstrated by transient expression in COS-1 cells. The mur ine alpha-GalNAc genomic sequence spanned similar to 9 kb and was iden tical in structure with the human alpha-GalNAc gene with eight introns interrupting the coding sequence at identical positions. In addition, the deduced amino acid sequence of the murine alpha-GalNAc gene was h ighly homologous with alpha-GalNAc and alpha-Gal A genes from other sp ecies providing further support for a common evolutionary ancestor of the alpha-galactosidase gene family. The availability of the murine ge ne will permit additional evolutionary comparisons, structure/function analyses, and the generation of mice with alpha-GalNAc deficiency by gene targeting. (C) 1998 Academic Press.