Neurochemical Research

, Volume 17, Issue 5, pp 509–528 | Cite as

The ligand binding site of the synaptosomal choline transporter: A provisional model based on inhibition studies

  • Eugene Roberts
  • Masao Tamaru
Original Articles


A topographic model of the ligand binding site of the choline transporter was deduced from inhibition studies with the help of CPK molecular models. It is posited that there are two identical or closely similar hydrophilic anionic sites separated from each other by an hinged, essentially planar but conformationally flexible cationic hydrophobic domain. Subsequently to attachment of external choline to either one of the anionic sites, both sites cooperate in enveloping the ligand by a Venus fly-trap mechanism. This leads to rapid configurational changes by which the closed-liganded form of the transporter opens up to the interior to release the bound choline. Intracellular K+, a ligand for the choline-binding site, is proposed to be countertransported by a reversal of the above mechanism.

Key Words

Choline transport ligand binding site inhibition structure-activity relationships model 


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Copyright information

© Plenum Publishing Corporation 1992

Authors and Affiliations

  • Eugene Roberts
    • 1
  • Masao Tamaru
    • 2
  1. 1.Department of NeurobiochemistryBeckman Research Institute of the City of HopeDuarte
  2. 2.Department of PhysiologyFujita Health University School of MedicineToyoakeJapan

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