glucuronyl-galactosyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase activity https://github.com/geneontology/go-ontology/issues/28762 https://github.com/geneontology/go-ontology/issues/30193 EC:2.4.1.223 Catalysis of the reaction: 3-O-(beta-D-GlcA-(1->3)-beta-D-Gal-(1->3)-beta-D-Gal-(1->4)-beta-D-Xyl)-L-seryl-[protein] + UDP-N-acetyl-alpha-D-glucosamine = 3-O-(alpha-D-GlcNAc-(1->4)-beta-D-GlcA-(1->3)-beta-D-Gal-(1->3)-beta-D-Gal-(1->4)-beta-D-Xyl)-L-seryl-[protein] + H+ + UDP. glucuronosylgalactosyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase activity Reactome:R-HSA-9953259 alpha-1,4-N-acetylglucosaminyltransferase activity GO:0001888 MetaCyc:2.4.1.223-RXN alpha-N-acetylglucosaminyltransferase I activity UDP-N-acetyl-D-glucosamine:beta-D-glucuronosyl-(1->3)-beta-D-galactosyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-xylosyl-proteoglycan 4IV-alpha-N-acetyl-D-glucosaminyltransferase activity RHEA:16221 molecular_function alpha1,4-N-acetylglucosaminyltransferase activity UDP-N-acetyl-D-glucosamine:beta-D-glucuronosyl-(1,3)-beta-D-galactosyl-(1,3)-beta-D-galactosyl-(1,4)-beta-D-xylosyl-proteoglycan 4IV-alpha-N-acetyl-D-glucosaminyltransferase activity acetylglucosaminyltransferase activity