CHT1 (High-Affinity Choline Transporter)
The neurotransmitter acetylcholine (ACh) interacts with the nicotinic and muscarinic ACh receptors and is involved in a variety of physiological, behavioral, and cognitive functions in the central and peripheral nervous system. ACh is synthesized from choline and acetyl coenzyme A by choline acetyltransferase in the cholinergic presynaptic terminals. Although it has long been recognized from classic studies on ACh metabolism that exogenous choline is critical for ACh synthesis, it was not until the 1970s that the existence of high-affinity choline transporters in cholinergic neurons was postulated based on studies using isolated nerve ending particles (synaptosomes). Extracellular choline is actively transported into the presynaptic terminals by the Na+-dependent, high-affinity choline transporter in the plasma membrane and subsequently used for ACh synthesis. The high-affinity choline uptake is the rate-limiting step in ACh synthesis....
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