CLONING AND EXPRESSION OF MOUSE UDP-GALNAC - POLYPEPTIDE N-ACETYLGALACTOSAMINYLTRANSFERASE-T3

A novel isoform of UDP-GalAc:polypeptide N-acetylgalactosaminyltransfe rase, designated ppGaN-Tase-T3, has been cloned from a mouse testis cD NA library and expressed in COS7 cells. ppGaNTase-T3 displayed 64 and 59% amino acid identity with ppGaNTase-T1 and ppGaNTase-T2, respective ly, and 96% amino acid identity with the recently reported human form of ppGaNTase-T3. The ppGaNTase-T3 transcript is abundant in the major salivary glands, gastrointestinal tract and both the male and female r eproductive systems. ppGaNTase-T3 and pDGaNTase-T1 display overlapping substrate preferences in vitro, although mapping studies of O-glycosy lated peptides suggests that certain hydroxyamino acids are preferenti ally glycosylated by each isoform. This suggests that more than one is oform of ppGaNTase may be required to complete the O-glycosylation of endogenous substrates. (C) 1996 Academic Press, Inc.