SLC10A4 is a member of the solute carrier family 10 that functions as a vesicular protein in cholinergic and monoaminergic neurons rather than a traditional bile acid transporter 1. The protein exhibits a seven transmembrane domain topology and is ubiquitously expressed in human tissues, with highest levels in brain, placenta, and liver 2. SLC10A4 localizes to synaptic vesicles and is particularly abundant in cholinergic neurons of the central nervous system, co-localizing with markers like choline acetyltransferase and vesicular acetylcholine transporter 1. Despite its similarity to bile acid transporters NTCP and ASBT, SLC10A4 shows no significant transport activity for bile acids under normal conditions 3. However, recent evidence suggests it may function as a protease-activated transporter, gaining bile acid transport activity following cleavage by proteases like thrombin 4. SLC10A4 forms homo- and heterodimers with other SLC10 family members, which may regulate its function 5. In disease contexts, SLC10A4 expression is depleted in Alzheimer's disease, correlating with neuronal degeneration severity 6, and knockout mice display altered dopaminergic signaling and sensory processing deficits relevant to neuropsychiatric disorders 7.