Apical Sodium-Dependent Bile Acid Transporter

Apical sodium-dependent bile acid transporter (ASBT, also known as IBAT-ileal bile acid transporter, SLC10A2) an ileal Na⁺-dependent transporter, actively reabsorbs bile acids (BAs) from the gut lumen. Bile acids are synthesized in the liver, stored in the gallbladder, and secreted into the duodenum at meals. ASBT is found on the brush border/apical membrane of ileal enterocytes, as well as the apical surface of renal tubules and cholangiocytes. Conjugated bile acids are actively transported by IBAT from the lumen/ apical side into the interior of the enterocyte and exported via the basolateral membrane organic solute transporter α/β heterodimer (OSTα/β; encoded by SLC51A/B) into the portal circulation, which allows for return of bile acids back to the liver. This process is a critical step in the enterohepatic circulation (EHC) of BAs and plays important roles in the homeostasis of BAs in the body. Therefore, ASBT is considered a favorite target for intervention to regulate the levels of BAs, cholesterol, lipid and glucose etc. In addition, ASBT is also a popular delivery target for developing prodrugs, due to its intestinal localization, high expression and high uptake capacity.