Solute carrier family 22 member 1 and 2 (OCT1 and OCT2) (OCT1/2)

Organic cation transporters 1 and 2 (OCT1 and OCT2) are essential membrane transport proteins encoded by the SLC22A1 and SLC22A2 genes, respectively (UniProt O15245, O15244). OCT1 is primarily expressed in the liver, where it mediates the uptake of various drugs and endogenous compounds from the blood into hepatocytes, while OCT2 is the predominant organic cation transporter in the kidney, facilitating the first step of renal tubular secretion (Koepsell, 2020, PMID: 32694158). These transporters are critical determinants of the pharmacokinetics of many widely used drugs, most notably the first-line antidiabetic agent metformin, which requires OCT1 for hepatic entry and OCT2 for renal elimination (Graham et al., 2011, PMID: 21383205). Beyond drug disposition, OCT2 is involved in the renal handling of creatinine, and its inhibition by drugs like dolutegravir or cimetidine can lead to benign increases in serum creatinine levels (Lepist et al., 2014, PMID: 24338209). Genetic variations in these transporters are known to influence drug efficacy and the risk of adverse reactions, such as cisplatin-induced nephrotoxicity, which is linked to OCT2-mediated accumulation in the kidneys (Filipski et al., 2009, PMID: 19193862). Consequently, OCT1 and OCT2 are recognized by regulatory agencies as key targets for evaluating potential drug-drug interactions during drug development (FDA, 2020).

Other names

SLC22A1SLC22A2Organic cation transporter 1Organic cation transporter 2hOCT1hOCT2

Facilitated diffusion of small organic cations across the plasma membrane driven by the electrochemical gradient of the substrate, without direct ATP consumption.