Probable glycosyltransferase. 3-O-{[(1->4)-beta-D-GlcA-(1->4)-alpha-D-GlcNAc](n)-(1->4)-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->4)-alpha-D-GlcNAc](n)-(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 Protein modification; protein glycosylation. Belongs to the glycosyltransferase 47 family. Exostosin-like 1