(N acetylneuraminyl) galactosylglucosylceramide N acetylgalactosaminyltransferase

(N-acetylneuraminyl)-galactosylglucosylceramide N-acetylgalactosaminyltransferase (EC 2.4.1.92, uridine diphosphoacetylgalactosamine-ganglioside GM3 acetylgalactosaminyltransferase, ganglioside GM2 synthase, ganglioside GM3 acetylgalactosaminyltransferase, GM2 synthase, UDP acetylgalactosamine-(N-acetylneuraminyl)-D-galactosyl-D-glucosylceramide acetylgalactosaminyltransferase, UDP-N-acetyl-D-galactosamine:1-O-[O-(N-acetyl-alpha-neuraminyl)-(2->3)-O-beta-D-galactopyranosyl-(1->4)-beta-D-glucopyranosyl]-ceramide 1,4-beta-N-acetyl-D-galactosaminyltransferase acetylgalactosaminyltransferase, UDP-N-acetylgalactosamine GM3 N-acetylgalactosaminyltransferase, uridine diphosphoacetylgalactosamine-acetylneuraminylgalactosylglucosylceramide acetylgalactosaminyltransferase, uridine diphosphoacetylgalactosamine-hematoside acetylgalactosaminyltransferase, GM2/GD2-synthase, beta-1,4N-aetylgalactosaminyltransferase, asialo-GM2 synthase, GalNAc-T, UDP-N-acetyl-D-galactosamine:(N-acetylneuraminyl)-D-galactosyl-D-glucosylceramide N-acetyl-D-galactosaminyltransferase) is an enzyme with systematic name UDP-N-acetyl-D-galactosamine:1-O-(O-(N-acetyl-alpha-neuraminyl)-(2->3)-O-beta-D-galactopyranosyl-(1->4)-beta-D-glucopyranosyl)-ceramide 4-beta-N-acetyl-D-galactosaminyltransferase. This enzyme catalyses the following chemical reaction

UDP-N-acetyl-D-galactosamine + 1-O-[O-(N-acetyl-alpha-neuraminyl)-(2->3)-O-beta-D-galactopyranosyl-(1->4)-beta-D-glucopyranosyl]-ceramide ⇌ UDP + 1-O-[O-2-(acetylamino)-2-deoxy-beta-D-galactopyranosyl-(1->4)-O-[N-acetyl-alpha-neuraminyl-(2->3)]-O-beta-D-galactopyranosyl-(1->4)-beta-D-glucopyranosyl]-ceramide

This enzyme catalyses the formation of the gangliosides (i.e. sialic-acid-containing glycosphingolipids) GM2, GD2 and SM2 from GM3, GD3 and SM3, respectively.