Mediates the transport of UDP-N-acetylglucosamine (UDP-GlcNAc) across the Golgi apparatus membrane (PubMed:30224661). Delivers an essential substrate for the maturation of N-glycans and the GlcNAc-containing glycosyl inositol phosphorylceramide (GIPC) class of sphingolipids in the Golgi apparatus (PubMed:30224661). A number of isoforms are produced. According to EST sequences. Expressed in roots, leaves, stems, flowers and siliques. No visible phenotype under normal growth conditions, but mutant plants have increased levels of high mannose N-glycans, decreased levels of complex N-glycans, and are insensitive to root growth inhibition by salt stress. Belongs to the TPT transporter family. UGnT (TC 2.A.7.15) subfamily.