N-acetyllactosaminide 3-alpha-galactosyltransferase

In enzymology, a N-acetyllactosaminide 3-alpha-galactosyltransferase is an enzyme that catalyzes the chemical reaction


 * UDP-galactose + beta-D-galactosyl-(1->4)-beta-N-acetyl-D-glucosaminyl-R $$\rightleftharpoons$$ UDP + alpha-D-galactosyl-(1->3)-beta-D-galactosyl-(1->4)-beta-N- acetylglucosaminyl-R

Thus, the two substrates of this enzyme are UDP-galactose and beta-D-galactosyl-(1->4)-beta-N-acetyl-D-glucosaminyl-R, whereas its 3 products are UDP, alpha-D-galactosyl-(1->3)-beta-D-galactosyl-(1->4)-beta-N-, and acetylglucosaminyl-R.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-galactose:N-acetyllactosaminide 3-alpha-D-galactosyltransferase. Other names in common use include alpha-galactosyltransferase, UDP-Gal:beta-D-Gal(1,4)-D-GlcNAc alpha(1,3)-galactosyltransferase, UDP-Gal:N-acetyllactosaminide alpha(1,3)-galactosyltransferase, UDP-Gal:N-acetyllactosaminide alpha-1,3-D-galactosyltransferase, UDP-Gal:Galbeta1->4GlcNAc-R alpha1->3-galactosyltransferase, UDP-galactose-acetyllactosamine alpha-D-galactosyltransferase, UDPgalactose:beta-D-galactosyl-beta-1,4-N-acetyl-D-glucosaminyl-, glycopeptide alpha-1,3-D-galactosyltransferase, glucosaminylglycopeptide alpha-1,3-galactosyltransferase, uridine diphosphogalactose-acetyllactosamine, alpha1->3-galactosyltransferase, uridine diphosphogalactose-acetyllactosamine galactosyltransferase, uridine, diphosphogalactose-, galactosylacetylglucosaminylgalactosylglucosylceramide, galactosyltransferase, beta-D-galactosyl-N-acetylglucosaminylglycopeptide, and alpha-1,3-galactosyltransferase. This enzyme participates in 3 metabolic pathways: glycosphingolipid biosynthesis - lactoseries, glycosphingolipid biosynthesis - neo-lactoseries, and glycan structures - biosynthesis 2.

Structural studies
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes, , and.