This gene encodes a liver-specific member of the organic anion transporter family. The encoded protein is a transmembrane receptor that mediates the sodium-independent uptake of numerous endogenous compounds including bilirubin, 17-beta-glucuronosyl estradiol and leukotriene C4. This protein is also involved in the removal of drug compounds such as statins, bromosulfophthalein and rifampin from the blood into the hepatocytes. Polymorphisms in the gene encoding this protein are associated with impaired transporter function.
Function
Mediates the Na+-independent uptake of organic anions (PubMed:10358072, PubMed:15159445, PubMed:17412826).
Shows broad substrate specificity, can transport both organic anions such as bile acid taurocholate (cholyltaurine) and conjugated steroids (dehydroepiandrosterone 3-sulfate, 17-beta-glucuronosyl estradiol, and estrone 3-sulfate), as well as eicosanoids (prostaglandin E2, thromboxane B2, leukotriene C4, and leukotriene E4), and thyroid hormones (T4 or L-thyroxine, and T3 or 3,3',5'-triiodo-L-thyronine) (PubMed:10358072, PubMed:10601278, PubMed:10873595, PubMed:12568656, PubMed:15159445, PubMed:15970799, PubMed:16627748, PubMed:17412826, PubMed:12196548).
Can take up bilirubin glucuronides from plasma into the liver, contributing to the detoxification-enhancing liver-blood shuttling loop (PubMed:22232210).
Involved in the clearance of endogenous and exogenous substrates from the liver (PubMed:10358072, PubMed:10601278).
Can transport HMG-CoA reductase inhibitors (also known as statins), such as pravastatin and pitavastatin, a clinically important class of hypolipidemic drugs (PubMed:10601278, PubMed:15970799, PubMed:15159445).
May play an important role in plasma and tissue distribution of the structurally diverse chemotherapeutic drug methotrexate (PubMed:23243220).
May also transport antihypertension agents, such as the angiotensin-converting enzyme (ACE) inhibitor prodrug enalapril, and the highly selective angiotensin II AT1-receptor antagonist valsartan, in the liver (PubMed:16627748, PubMed:16624871).
Biological Process
Biological Process bile acid and bile salt transportManual Assertion Based On ExperimentIBA:GO_Central
Biological Process heme catabolic processTAS:Reactome
Biological Process organic anion transportManual Assertion Based On ExperimentTAS:ProtInc
Biological Process sodium-independent organic anion transportManual Assertion Based On ExperimentIBA:GO_Central
Biological Process xenobiotic metabolic processTAS:Reactome
Involvement in disease
Hyperbilirubinemia, Rotor type (HBLRR):
An autosomal recessive form of primary conjugated hyperbilirubinemia. Affected individuals develop mild jaundice not associated with hemolysis shortly after birth or in childhood. They have delayed plasma clearance of the unconjugated anionic dye bromsulphthalein and prominent urinary excretion of coproporphyrin I. Hepatic pigmentation is normal.