As a major transporter of conjugated bile salts from plasma into the hepatocyte, it plays a key role in the enterohepatic circulation of bile salts necessary for the solubilization and absorption of dietary fat and fat-soluble vitamins ( , ). It is strictly dependent on the extracellular presence of sodium ( , ). It exhibits broad substrate specificity and transports various bile acids, such as taurocholate, cholate, as well as non-bile acid organic compounds, such as estrone sulfate (, ). Works collaboratively with the ileal transporter (NTCP2), the organic solute transporter (OST), and the bile salt export pump (BSEP), to ensure efficacious biological recycling of bile acids during enterohepatic circulation .
(Microbial infection) Acts as a receptor for hepatitis B virus.
Subcellular locations: Cell membrane
Expressed in liver (, ). Expressed in placental trophoblasts .