Genomic organization and chromosomal localization of three members of the UDP-N-acetylgalactosamine: Polypeptide N-acetylgalactosaminyltransferase family

Abstract

A homologous family of UDP-N-acetylgalactosamine: polypeptide N- acetylgalactosaminyltransferases (GalNAc-transferases) initiate O- glycosylation. These transferases share overall amino acid sequence similarities of approximately 45-50%, but segments with higher similarities of ~80% are found in the putative catalytic domain. Here we have characterized the genomic organization of the coding regions of three GalNAc- transferase genes and determined their chromosomal localization. The coding regions of GALNT1, -T2, and -T3 were found to span 11,16, and 10 exons, respectively. Several intron/exon boundaries were conserved within the three genes. One conserved boundary was shared in a homologous C.elegans GalNAc- transferase gene. Fluorescence in situ hybridization showed that GALNT1, - T2, and -T3 are localized at chromosomes 18q12-q21, 1q41-q42, and 2q24-q31, respectively. These results suggest that the members of the polypeptide GalNAc-transferase family diverged early in evolution from a common ancestral gene through gene duplication.