The members of the solute carrier family 45 (SLC45) have been implicated with the regulation of glucose homeostasis in the brain (SLC45A1), skin and hair pigmentation (SLC45A2), prostate cancer and myelination (SLC45A3). However, apart from A1, a proton-associated glucose transporter, the function of these proteins is still largely unknown. Sequence similarities to plant sucrose transporters mark them as a putative sucrose transporter family. By expressing the three members SLC45A2, SLC45A3 and SLC45A4 in yeast and measuring ¹⁴C-sucrose uptake, we can show that these transporters are indeed proton-coupled sugar transporters with an unusual spectrum. Out of 13 tested sugars, glucose, fructose and mannose, but also sucrose, were the preferred substrates. This is a quite different spectrum from what is known from the sodium glucose cotransporter family SLC5 and the facilitative glucose transporter family SLC2. It is also just as unusual for mammalian sugar transporters that transport is coupled to that of protons. However, most astonishing is the transport of sucrose, as there are no other sugar transporters in mammals known to transport disaccharides. In fact, the lack of transmembrane disaccharide transport in mammals is a widely accepted textbook truth that needs to be revised.