Main pageKEGG pathway → Glycosaminoglycan biosynthesis

KEGG pathway: Glycosaminoglycan biosynthesis

Pathway hsa00532
Name Glycosaminoglycan biosynthesis
Members DSE CHST14 UST CHST3 CHSY1 CHST11 CHPF CHPF2 CHST12 CHST7 B4GALT7 B3GALT6 XYLT2 CHST13 B3GAT3 CSGALNACT2 B3GAT2 CHST15 XYLT1 CSGALNACT1 CHSY3 B3GAT1
Description Glycosaminoglycans (GAGs) are linear polysaccharide chains consisting of repeating disaccharide units and form proteglycans by covalently attaching to their core proteins. Chondroitin sulfate (CS) is a glycosaminoglycan with the disaccharide unit GalNAc(b1-4)GlcA(b1-3), modified with ester-linked sulfate at certain positions. Dermatan sulfate (DS) is a modified form of CS, in which a portion of D-glucuronate residues is epimerized to L-iduronates. CS and DS are linked to serine residues in core proteins via a linkage tetrasaccharide formed by the transfer of xylose and three more residues [MD:M00057]. The assembly process of CS is initiated by the transfer of N-acetylgalactosamine to the linkage tetrasaccharide. The polymerization step is catalyzed by bifunctional enzymes (chondroitin synthases) that have both b1-3 glucuronosyltransferase and b1-4 N-acetylgalactosaminyltransferase activities [MD:M00058]. Chondroitin polymerization also requires the action of the chondroitin polymerizing factor. Sulfation of chondroitin in vertebrates is a complex process, with multiple sulfotransferases involved in 4-O sulfation and 6-O sulfation of N-acetylgalactosamine residues. Additional enzymes exist for epimerization of glucuronic acid to iduronic acid in DS, sulfation at the C-2 position of the uronic acids, and other patterns of sulfation found in unusual species of chondroitin.