Organic Cation Transporter OCTs (SLC22) and MATEs (SLC47) in the Human Kidney

In the kidney, human organic cation transporters (OCTs) and multidrug and toxin extrusion proteins (MATEs) are the major transporters for the secretion of cationic drugs into the urine. In the human kidney, OCT2 mediates the uptake of drugs from the blood at the basolateral membrane of tubular epithelial cells, and MATE1 and MATE2-K secrete drugs from cells into the lumen of proximal tubules. However, the expression of these transporters depends on the species of the animal. In the rodent kidney, OCT1 and OCT2 are expressed at the basolateral membrane, and MATE1 localizes at the brush-border membrane. Together, these transporters recognize various compounds and have overlapping, but somewhat different, substrate specificities. OCTs and MATEs can transport important drugs, such as metformin and cisplatin. Therefore, functional variation in OCTs and MATEs, including genetic polymorphisms or inter-individual variation, may seriously affect the pharmacokinetics and/or pharmacodynamics of cationic drugs. In this review, we summarize the recent findings and clinical importance of these transporters.