Galactosylgalactosylxylosylprotein 3-beta-glucuronosyltransferase 3 (EC 2.4.1.135) (Beta-1,3-glucuronyltransferase 3) (Glucuronosyltransferase I) (GlcAT-I) (UDP-GlcUA:Gal beta-1,3-Gal-R glucuronyltransferase) (GlcUAT-I)
1_MKLKL 6_ KNVFL 11_ AYFLV 16_ SIAGL 21_ LYALV 26_ QLGQP 31_ CDCLP 36_ PLRAA 41_ AEQLR 46_ QKDLR 51_ ISQLQ 56_ AELRR 61_ PPPAP 66_ AQPPE 71_ PEALP 76_ TIYVV 81_ TPTYA 86_ RLVQK 91_ AELVR 96_ LSQTL 101_ SLVPR 106_ LHWLL 111_ VEDAE 116_ GPTPL 121_ VSGLL 126_ AASGL 131_ LFTHL 136_ VVLTP 141_ KAQRL 146_ REGEP 151_ GWVHP 156_ RGVEQ 161_ RNKAL 166_ DWLRG 171_ RGGAV 176_ GGEKD 181_ PPPPG 186_ TQGVV 191_ YFADD 196_ DNTYS 201_ RELFE 206_ EMRWT 211_ RGVSV 216_ WPVGL 221_ VGGLR 226_ FEGPQ 231_ VQDGR 236_ VVGFH 241_ TAWEP 246_ SRPFP 251_ VDMAG 256_ FAVAL 261_ PLLLD 266_ KPNAQ 271_ FDSTA 276_ PRGHL 281_ ESSLL 286_ SHLVD 291_ PKDLE 296_ PRAAN 301_ CTRVL 306_ VWHTR 311_ TEKPK 316_ MKQEE 321_ QLQRQ 326_GRGSD
1: Glycosaminoglycans biosynthesis (PubMed:25893793). Involved in forming the linkage tetrasaccharide present in heparan sulfate and chondroitin sulfate. Transfers a glucuronic acid moiety from the uridine diphosphate-glucuronic acid (UDP-GlcUA) to the common linkage region trisaccharide Gal-beta-1,3-Gal-beta-1,4-Xyl covalently bound to a Ser residue at the glycosaminylglycan attachment site of proteoglycans. Can also play a role in the biosynthesis of l2/HNK-1 carbohydrate epitope on glycoproteins. Shows strict specificity for Gal-beta-1,3-Gal-beta-1,4-Xyl, exhibiting negligible incorporation into other galactoside substrates including Galbeta1-3Gal beta1-O-benzyl, Galbeta1-4GlcNAc and Galbeta1-4Glc. Stimulates 2-phosphoxylose phosphatase activity of PXYLP1 in presence of uridine diphosphate-glucuronic acid (UDP-GlcUA) during completion of linkage region formation (PubMed:24425863)