Fig. 1.

Basic membrane topology of a prototypical OATP/Oatp transporter. OATP/Oatp family members are predicted to follow a 12-transmembrane domain topology where the OATP superfamily signature sequence is depicted at the junction between the third extracellular loop and transmembrane domain 6. Conserved cysteine residues are localized to the fifth extracellular loop. Additionally, three predicted glycosylation sites (Y) are demarcated on extracellular loops 2 and 5.