Glycosyltransferase required for the biosynthesis of heparan sulfate (PubMed:11121397, PubMed:16828468, PubMed:17237233). Initiates heparan sulfate synthesis by transferring GlcNAc to the (GlcA-Gal-Gal-Xyl-)Ser core linker (GlcNAcT-I activity) (PubMed:11121397). In association with rib-1, is also responsible for the alternating addition of beta-1-4-linked glucuronic acid (GlcA) and alpha-1-4-linked N-acetylglucosamine (GlcNAc) units to nascent heparan sulfate chains (GlcNAcT-II and GlcAT-II activities) (PubMed:11121397, PubMed:17237233). Required for normal ventral epidermal enclosure during the early stages of embryonic development (PubMed:17237233). In addition, involved in the elongation of the pharyngeal isthmus during the later stages of embryonic development (PubMed:16828468). Involved in the directed migration of hermaphrodite-specific neurons (PubMed:17237233, PubMed:24052309). 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 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 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] + UDP-alpha-D-glucuronate = 3-O-{[(1->4)-beta-D-GlcA-(1->4)-alpha-D-GlcNAc](n+1)-(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 Binding to rib-1 is required for GlcAT-II activity and for increasing GlcNAc-II activity in vitro. Glycan metabolism; heparan sulfate biosynthesis. Interacts with rib-1. Mutant embryos are arrested at the 1-fold stage due to a failure in epidermal enclosure (PubMed:17237233). RNAi-mediated knockdown results in the failure of hermaphrodite-specific neurons to migrate to their correct position and in a defect in axonal guidance (PubMed:24052309). Belongs to the glycosyltransferase 47 family.