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 of beta-D-galactosamine (GalNAc) and beta-D-glucuronic acid (GlcA), and often 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 (IdoA). 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 transferring GalNAc residue to the linkage tetrasaccharide. The polymerization is catalyzed by bifunctional enzymes (chondroitin synthases) possessing both beta 1,3 glucuronosyltransferase and beta 1,4 N-acetylgalactosaminyltransferase activities [MD:M00058]. Chondroitin polymerization also requires the action of the chondroitin polymerizing factor. There are various O-sulfation patterns in CS and DS, where 4-O sulfation and 6-O sulfation of GalNAc and 2-O-sulfation of the uronic acids (GlcA / IdoA) are mainly found

external resources
NCBI:82982
KEGG:hsa00532
PUBMED:12847091
PUBMED:22899863
PUBMED:19661164
PUBMED:11551958
PUBMED:11274177
PUBMED:17253960
PUBMED:14568616
PUBMED:12716890
PUBMED:9506957
PUBMED:11042448
PUBMED:17239763
PUBMED:21138417
PUBMED:17928217
PUBMED:10473568
PUBMED:12512856
PUBMED:11099377

genes
CHST3 , UST , B4GALT7 , CHSY1 , B3GAT3 , DSE , CHST11 , CHST15 , CHPF2 , CSGALNACT2 , CHST12 , CSGALNACT1 , CHST7 , XYLT1 , XYLT2 , CHPF , CHST14 , B3GALT6 , CHST13 , CHSY3 ,