Organic anion transporting polypeptide 1B1 (OATP1B1), 1B3 (OATP1B3), and 2B1 (OATP2B1) (OATP1B1/1B3/2B1)

Organic anion transporting polypeptides 1B1, 1B3, and 2B1 are critical membrane transporters belonging to the SLCO superfamily, primarily localized on the sinusoidal (basolateral) membrane of human hepatocytes [1, 2]. They facilitate the sodium-independent uptake of a diverse array of endogenous substances, such as bilirubin, bile acids, and steroid conjugates, as well as numerous clinically important drugs, including statins, antivirals, and chemotherapeutic agents [3, 11]. OATP1B1 and OATP1B3 are exclusively expressed in the liver, while OATP2B1 has a broader tissue distribution including the intestine and blood-brain barrier [4, 8]. These transporters play a pivotal role in the first-pass effect and overall hepatic clearance of their substrates [15]. Genetic variations, such as the SLCO1B1*5 polymorphism, or pharmacological inhibition by drugs like cyclosporine or rifampin, can lead to markedly increased plasma concentrations of substrate drugs, significantly raising the risk of adverse effects like statin-induced myopathy or rhabdomyolysis [7, 10]. Due to their profound impact on pharmacokinetics and safety, they are recognized by regulatory agencies as key targets for evaluating drug-drug interaction potential during drug development [9, 12].

Other names

SLCO1B1SLCO1B3SLCO2B1Solute carrier organic anion transporter family member 1B1Solute carrier organic anion transporter family member 1B3Solute carrier organic anion transporter family member 2B1Liver-specific organic anion transporter 1 (LST-1)OATP-COATP-8OATP-2

These proteins function as sodium-independent uptake transporters that facilitate the diffusion of amphipathic organic anions across the basolateral membrane of hepatocytes. Drugs targeting or interacting with these transporters typically act as substrates (undergoing hepatic clearance) or inhibitors (blocking the uptake of other drugs, leading to increased systemic exposure and potential toxicity).