The human multidrug and toxin extrusion transporter 1 (hMATE1; SLC47A1) is highly expressed on the apical side of renal proximal and distal tubule cells and on the canalicular membrane of hepatocytes. There MATE1 is acting as electroneutral exchanger of its substrates with oppositely directed proton gradient as a driving force. Although export is the presumed physiological role, depending on the intracellular and extracellular pH, MATEs may also act as an uptake transporter. Typical substrates for MATEs are hydrophilic, low-molecular-weight organic cations such as metformin and 1-methy-4-phenylpyridinium (MPP).
Inhibition of hMATE1-mediated metformin uptake by different inhibitors (100 µM)