Glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase

In enzymology, a glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase (EC 2.4.1.122) is an enzyme that catalyzes the chemical reaction

UDP-galactose + glycoprotein N-acetyl-D-galactosamine UDP + glycoprotein D-galactosyl-1,3-N-acetyl-D-galactosamine

Thus, the two substrates of this enzyme are UDP-galactose and glycoprotein N-acetyl-D-galactosamine, whereas its two products are UDP and glycoprotein D-galactosyl-1,3-N-acetyl-D-galactosamine.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-galactose:glycoprotein-N-acetyl-D-galactosamine 3-beta-D-galactosyltransferase. This enzyme is also called uridine diphosphogalactose-mucin beta-(1->3)-galactosyltransferase. This enzyme participates in o-glycan biosynthesis and glycan structures - biosynthesis 1.