Organic cation transporter 1 and OATP transporters (OCT1 and OATP)

Organic cation transporter 1 (OCT1) and organic anion transporting polypeptides (OATPs) are membrane-bound solute carrier transporters critical for the uptake of structurally diverse endogenous and exogenous compounds, including many clinically important drugs. OCT1 (SLC22A1) primarily transports organic cations and is important for hepatic uptake and clearance of drugs such as metformin. OATPs (SLCO family) mediate the sodium-independent uptake of large, amphipathic organic anions and some neutral or cationic drugs, playing a vital role in hepatic drug clearance, bile acid and hormone transport, and are important for the pharmacokinetics and safety of numerous drugs, especially statins, antibiotics, and anticancer agents. Both transporter types are highly expressed in the liver and other tissues, are subject to significant genetic variation, and are frequent sites of clinically important drug–drug interactions. Altered function or expression impacts disease risk, drug safety, and therapeutic response, making them important pharmacogenomic biomarkers and therapeutic targets.

Other names

OCT1: SLC22A1, solute carrier family 22 member 1OATP: SLCO family (e.g., SLCO1B1, SLCO1B3, SLCO2B1), organic anion transporter polypeptide, OATPs

Facilitate cellular uptake of cationic (OCT1) or anionic (OATPs) drugs and metabolites through Na+-independent facilitated diffusion, often acting as exchangers (e.g., exchanging organic cations/anions with other intracellular solutes). Substrate recognition is poly-specific, with overlap between drugs and endogenous molecules.