PRIMARY STRUCTURE AND FUNCTIONAL EXPRESSION OF A CHOLINE TRANSPORTER EXPRESSED IN THE RAT NERVOUS-SYSTEM

Synthesis of the neurotransmitter acetylcholine in cholinergic nerve terminals is regulated by a sodium-driven high-affinity choline uptake system in the plasma membrane. We have isolated cDNAs from rat spinal cord and brainstem which encode a choline transporter (CHOT1). The predicted protein shares considerable amino acid identity and several structural features including twelve putative transmembrane regions with other neurotransmitter transporters. Expression of in vitro transcribed CHOT1 RNA in Xenopus oocytes generated Na+-dependent choline uptake, which was not seen in control oocytes. Amplification by polymerase chain reaction (PCR) revealed significant amounts of CHOT1 mRNA in brain. cerebellum, spinal cord and, to a lesser extent. heart, but only very low expression in lung, kidney and muscle.