The biosynthetic pathways of heparan sulfate and chondroitin sulfate/dermatan sulfate. HS, heparan sulfate; CS, chondroitin sulfate; DS, dermatan sulfate; 2S, 2-O-sulfation; 6S, 6-O-sulfation; 3S, 3-O-sulfation; 4S, 4-O-sulfation; NS, N-sulfated glucosamine. XylT1/2, xylosyltransferase 1/2; FAM20B, family with sequence similarity member 20-B; PXYLP1, 2-phosphoxylose phosphatase; GalT-I, galactosyltransferase-I; GalT-II, galactosyltransferase-II; GlcAT-Ⅰ, glucuronyltransferase-Ⅰ;
EXT1, exostosin glycosyltransferase 1; EXT2, exostosin glycosyltransferase 2; EXTL1, exostosin like glycosyltransferase 1; EXTL2, exostosin like glycosyltransferase 2; EXTL3, exostosin like glycosyltransferase 3; NDST1, N-sulfotransferase; NDST2, N-sulfotransferase 2; NDST3, N-sulfotransferase 3; NDST4, N-sulfotransferase 4; HS6ST1, heparan sulfate 6-O-sulfotransferase 1; HS6ST2, heparan sulfate 6-O-sulfotransferase 2; HS6ST3, heparan sulfate 6-O-sulfotransferase 3; HS3ST1, heparan sulfate 3-O-sulfotransferase 1; HS3ST2, heparan sulfate 3-O-sulfotransferase 2; HS3ST3a, heparan sulfate 3-O-sulfotransferase 3a; HS3ST3b, heparan sulfate 3-O-sulfotransferase 3b; HS3ST4, heparan sulfate 3-O-sulfotransferase 4; HS3ST5, heparan sulfate 3-O-sulfotransferase 5; HS3ST6, heparan sulfate 3-O-sulfotransferase 6;
GLCE, C-5 epimerase; HS2ST, heparan sulfate 2-O-sulfotransferase; GalNAcT- I, GalNAc transferase-I; GalNAcT- IIs, GalNAc transferase-II; GlcAT- II,β1,3-glucuronyltransferase- II; C4ST, chondroitin 4-O-sulfotransferase; C6ST,; GalNAc4S-6ST,; UST, uronyl 2-O-sulfotransferase; DSE1, DS epimerase1; DSE2, DS epimerase2; D4ST, dermatan 4-O-sulfotransferase; GalNAc4S-6ST, GalNAc 4-sulfate 6-O-sulfotransferase. Monosaccharides in this figure are represented in accordance with the symbol nomenclature for glycans (SNFG) (Varki et al., 2015).