Bile salt and acid uptake across the apical membrane of ileal enterocytes is mediated mainly by the apical sodium-dependent bile acid transporter, ASBT, whereas basolateral efflux into the portal blood system is mediated largely by the heterodimeric organic solute transporter SLC51A:SLC51B (OSTA:OSTB) (Seward et al. 2003, Ballatori et al. 2005). Heterodimerization of SLC51 alpha and beta subunits is required not only for plasma membrane localisation but also for increased stability of the proteins (Li et al. 2007).
bile acid transmembrane transporter activity of SLC51A:SLC51B [plasma membrane]