As a major transporter of conjugated bile salts from plasma into the hepatocyte, it has a key role in the enterohepatic circulation of bile salts necessary for the solubilization and absorption of dietary fat and fat-soluble vitamins. It exhibits broad substrate specificity and transports various non-bile acid organic compounds as well. It is strictly dependent on the extracellular presence of sodium. Able to transport taurocholate, cholate, and the non-bile acid estron sulfate (PubMed:14660639, PubMed:24867799). (Microbial infection) Acts as a receptor for hepatitis B virus. (Microbial infection) Interacts with hepatitis B virus large envelope protein. The disease is caused by variants affecting the gene represented in this entry. Belongs to the bile acid:sodium symporter (BASS) (TC 2.A.28) family.