Neurotransmitter transporters: Molecular biology, function, and regulation

This chapter discusses the molecular biology, functions, and regulation of neurotransmitter transporters. Acetylcholine is the only major classical neurotransmitter without a transporter. The two major functions of these plasma membrane-bound transporters, inactivation and recycling of released neurotransmitter, are accomplished by different mechanisms for acetycholine. Released acetylcholine is enzymatically degraded, and choline, a precursor for the synthesis of acetylcholine, is taken back into the terminal by a specific transporter. Interest in transport and transporters is focused on a wide spectrum of topics ranging from basic neurochemistry to drug development. The more basic research includes the mechanism of action of transporters as well as their roles in neurotransmission and transmitter recycling. In addition, transporters are useful tools for identifying and characterizing neurotransmitter systems. The ligand-binding domains of neurotransmitter receptors provide clues to the binding of the substrates to their transporters. For example, two serine residues in the fifth transmembrane domain of adrenergic receptors are proposed to act as a hydrogen bond donor in the binding of the hydroxyl group of the catechol ring. © 1995, Academic Press Inc.