ExplorEnz: EC 2.4.1.175

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2.4.1.175

Accepted name:

glucuronosyl-N-acetylgalactosaminyl-proteoglycan 4-β-N-acetylgalactosaminyltransferase

Reaction:

(1) UDP-N-acetyl-α-D-galactosamine + [protein]-3-O-(β-D-GlcA-(1→3)-β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl)-L-serine = UDP + [protein]-3-O-(β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)-β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl)-L-serine
(2) UDP-N-acetyl-α-D-galactosamine + [protein]-3-O-(β-D-GlcA-(1→3)-[β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)]_n-β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl)-L-serine = UDP + [protein]-3-O-([β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)]_n+1-β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl)-L-serine

For diagram of chondroitin biosynthesis (later stages), click here

Other name(s):

N-acetylgalactosaminyltransferase II; UDP-N-acetyl-D-galactosamine:D-glucuronyl-N-acetyl-1,3-β-D-galactosaminylproteoglycan β-1,4-N-acetylgalactosaminyltransferase; chondroitin synthase; glucuronyl-N-acetylgalactosaminylproteoglycan β-1,4-N-acetylgalactosaminyltransferase; uridine diphosphoacetylgalactosamine-chondroitin acetylgalactosaminyltransferase II; UDP-N-acetyl-D-galactosamine:β-D-glucuronosyl-(1→3)-N-acetyl-β-D-galactosaminyl-proteoglycan 4-β-N-acetylgalactosaminyltransferase; UDP-N-acetyl-α-D-galactosamine:β-D-glucuronosyl-(1→3)-N-acetyl-β-D-galactosaminyl-proteoglycan 4-β-N-acetylgalactosaminyltransferase

Systematic name:

UDP-N-acetyl-α-D-galactosamine:[protein]-3-O-(β-D-GlcA-(1→3)-β-D-GalNAc-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl)-L-serine 4-β-N-acetylgalactosaminyltransferase (configuration-inverting)

Comments:

Involved in the biosynthesis of chondroitin sulfate. The human form of this enzyme is a bifunctional glycosyltransferase, which also has the 3-β-glucuronosyltransferase (EC 2.4.1.226, N-acetylgalactosaminyl-proteoglycan 3-β-glucuronosyltransferase) activity required for the synthesis of the chondroitin sulfate disaccharide repeats. Similar chondroitin synthase ’co-polymerases’ can be found in Pasteurella multocida and Escherichia coli.

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 96189-40-1

References:

1.	Rohrmann, K., Niemann, R. and Buddecke, E. Two N-acetylgalactosaminyltransferases are involved in the biosynthesis of chondroitin sulfate. Eur. J. Biochem. 148 (1985) 463–469. [DOI] [PMID: 3922754]
2.	Kitagawa, H., Uyama, T. and Sugahara, K. Molecular cloning and expression of a human chondroitin synthase. J. Biol. Chem. 276 (2001) 38721–38726. [DOI] [PMID: 11514575]
3.	DeAngelis, P.L. and Padgett-McCue, A.J. Identification and molecular cloning of a chondroitin synthase from Pasteurella multocida type F. J. Biol. Chem. 275 (2000) 24124–24129. [DOI] [PMID: 10818104]
4.	Ninomiya, T., Sugiura, N., Tawada, A., Sugimoto, K., Watanabe, H. and Kimata, K. Molecular cloning and characterization of chondroitin polymerase from Escherichia coli strain K4. J. Biol. Chem. 277 (2002) 21567–21575. [DOI] [PMID: 11943778]

[EC 2.4.1.175 created 1989, modified 2002]