Antiporter that transports nucleotide sugars across the endoplasmic reticulum (ER) membrane in exchange for either their cognate nucleoside monophosphate or another nucleotide sugar ( ). Transports various UDP-sugars including UDP-N-acetyl-alpha-D-glucosamine (UDP-GlcNAc), UDP-N-acetyl-alpha-D-galactosamine (UDP-GalNAc) and UDP-alpha-D-glucuronate (UDP-GlcA), which are used by ER glucosyltransferases as sugar donors for the synthesis of sugar chains of glycoproteins, glycolipids and oligosaccharides (  ). May couple UDP-GlcNAc or UDP-GalNAc efflux to UDP-GlcA influx into the ER lumen that in turn stimulates glucuronidation and subsequent excretion of endobiotics and xenobiotics (, ). Plays a role in chondroitin sulfate biosynthesis, which is important for formation of cartilage extracellular matrix and normal skeletal development (By similarity).
Subcellular locations: Endoplasmic reticulum membrane
Ubiquitous.