N-acetylgalactosaminide beta-1,3-galactosyltransferase activity https://github.com/geneontology/go-ontology/issues/30971 Core 1 GalT EC:2.4.1.122 UDPgalactose:glycoprotein-N-acetyl-D-galactosamine 3-beta-D-galactosyltransferase activity RHEA:36763 RHEA:15621 GO:0016263 MetaCyc:RXN-18266 RHEA:56200 Reactome:R-HSA-6785524 glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase activity Reactome:R-HSA-1964505 Catalysis of the reaction: an N-acetyl-alpha-D-galactosaminyl derivative + UDP-alpha-D-galactose = a beta-D-galactosyl-(1->3)-N-acetyl-alpha-D-galactosaminyl derivative + UDP + H+. uridine diphosphogalactose-mucin beta-(1->3)-galactosyltransferase activity RHEA:56196 molecular_function UDP-galactose:glycoprotein-N-acetyl-D-galactosamine 3-beta-D-galactosyltransferase activity UDP-galactosyltransferase activity beta-1,3-galactosyltransferase activity catalytic activity, acting on a glycoprotein