ID 2.4.1.223 DE glucuronosyl-galactosyl-proteoglycan 4-alpha-N- DE acetylglucosaminyltransferase. AN alpha1,4-N-acetylglucosaminyltransferase. AN alpha-N-acetylglucosaminyltransferase I. AN glucuronosylgalactosyl-proteoglycan 4-alpha-N- AN acetylglucosaminyltransferase. AN glucuronyl-galactosyl-proteoglycan 4-alpha-N- AN acetylglucosaminyltransferase. CA 3-O-(beta-D-GlcA-(1->3)-beta-D-Gal-(1->3)-beta-D-Gal-(1->4)-beta-D-Xyl)- CA L-seryl-[protein] + UDP-N-acetyl-alpha-D-glucosamine = 3-O-(alpha-D- CA GlcNAc-(1->4)-beta-D-GlcA-(1->3)-beta-D-Gal-(1->3)-beta-D-Gal-(1->4)- CA beta-D-Xyl)-L-seryl-[protein] + H(+) + UDP. CC -!- Enzyme involved in the initiation of heparin and heparan sulfate CC synthesis, transferring GlcNAc to the (GlcA-Gal-Gal-Xyl-)Ser core. CC -!- Apparently products of both the human EXTL2 and EXTL3 genes can CC catalyze this reaction. CC -!- In Caenorhabditis elegans, the product of the rib-2 gene displays CC this activity as well as that of EC 2.4.1.224. DR O01705, EXT2_CAEEL ; Q9XZ08, EXT3_DROME ; Q9UBQ6, EXTL2_HUMAN; DR Q9ES89, EXTL2_MOUSE; O43909, EXTL3_HUMAN; Q9WVL6, EXTL3_MOUSE; //