This gene encodes a member of the GalNAc polypeptide N-acetylgalactosaminyltransferases. These enzymes catalyze the first step in the synthesis of mucin-type oligosaccharides. These proteins transfer GalNAc from UDP-GalNAc to either serine or threonine residues of polypeptide acceptors. The protein encoded by this locus may have increased catalytic activity toward glycosylated peptides compared to activity toward non-glycosylated peptides.[provided by RefSeq, Apr 2010].