Transporter for bile acids. Mainly expressed in the central nervous system cholinergic neurons. Expressed (at protein level) in motor regions of the spinal cord and rhombencephalon, in mesopontine cholinergic neurons, the medial habenula, cholinergic areas of the forebrain, and the gut myenteric plexus. Activated following N-terminal proteolytic cleavage by thrombin and/or proteases. Belongs to the bile acid:sodium symporter (BASS) (TC 2.A.28) family.