The organic anion transporter 3 (OAT-3 or SLC22A8) is localized to the basolateral membrane of renal tubular epithelial cells and plays a critical role in the e, Xenopus/Amphibian,cretion and deto, Xenopus/Amphibian,ification of anionic compounds. Recent works have identified three organic anion transporter families: the organic anion transporter (OAT) family encoded by SLC22A, the organic anion transporting peptide (OATP) family encoded by SLC21A, and the multidrug resistance-associatred protein (MRP) family encoded by ABCC. These family members are involved in the transepithelial transport of organic anions in many tissues such as kidney, liver and brain.