Mediates the transport of adenosine 3'-phospho 5'-phosphosulfate (PAPS), from cytosol into Golgi. PAPS is a universal sulfuryl donor for sulfation events that take place in the Golgi. Required for the dorsoventral patterning, suggesting that it mediates the transport of the sulfate donor required for the sulfotransferase activity of pip (pipe). Expressed throughout embryogenesis. During oogenesis, it is expressed strongly in the nurse cells of the germline. Maternally expressed at the syncytial blastoderm stage. Zygotically expressed, from after germ-band elongation in the invaginating salivary gland placodes. Remains expressed predominantly in this tissue throughout embryogenesis, but low-level expression may also be present throughout the embryo. Expressed both maternally and zygotically. Flies display defects in wingless (wg) and hedgehog (hh) signaling, probably due to the lack of sulfation of glycosaminoglycans by sulfotransferases such as sfl. Belongs to the nucleotide-sugar transporter family. SLC35B subfamily.