High-affinity Na(+)-coupled choline transmembrane symporter (   , ). Functions as an electrogenic, voltage-dependent transporter with variable charge/choline stoichiometry . Choline uptake and choline-induced current is also Cl(-)-dependent where Cl(-) is likely a regulatory ion rather than cotransported ion ( ). Plays a critical role in acetylcholine (ACh) synthesis by taking up the substrate choline from the synaptic cleft into the presynaptic nerve terminals after neurotransmitter release . SLC5A7/CHT1-mediated choline high-affinity transport in cholinergic neurons is the rate-limiting step for production of ACh, thereby facilitating communication by subsequent action potentials . Localized predominantly in presynaptic terminal intracellular organelles, and translocated to the plasma membrane in active form in response to neuronal activity (, ).
Subcellular locations: Presynaptic cell membrane, Cell projection, Axon, Early endosome membrane, Cytoplasmic vesicle, Secretory vesicle, Synaptic vesicle membrane
Localized at the neuromuscular junction . Localization at the plasma membrane is transient due to the rapid endocytosis of SLC5A7/CHT1 via the clathrin-mediated pathway, where it localizes to early endosomes (, ). Also localized to synaptic vesicles where it is likely mobilized to the cell surface by exocytosis .
Expressed in putamen, spinal cord and medulla (, ). Expressed in cholinergic neurons .