Transports nucleotide sugars from the cytosol into Golgi vesicles where glycosyltransferases function. Interacts with SLC35A3; the interaction is reduced in the presence of SLC35A4 (By similarity). Found in a complex with SLC35A3 and SLC35A4 (By similarity). Belongs to the nucleotide-sugar transporter family. SLC35A subfamily.