MFSD8 is a ubiquitous integral membrane protein that contains a transporter domain and a major facilitator superfamily (MFS) domain. Other members of the major facilitator superfamily transport small solutes through chemiosmotic ion gradients. The substrate transported by this protein is unknown. The protein likely localizes to lysosomal membranes.The MFSD8 gene was predicted to encode a 518-amino acid protein of approximately 58 kD with 12 predicted transmembrane domains. Pfam analysis of the MFSD8 amino acid sequence showed that it contains an MFS domain at amino acid positions 42 through 477 and a sugar (and other) transporter domain at amino acid positions 72 through 147. MFSD8 appeared to be evolutionarily conserved, since a BLAST search returned several homologs for MFSD8 in different species.