The Journal of Neuroscience, August 1, 1998, 18(15):5555-5564
Formation of the Nicotinic Acetylcholine Receptor Binding
Sites
William N.
Green and
Christian P.
Wanamaker
Department of Pharmacological and Physiological Sciences,
University of Chicago, Chicago, Illinois 60637
Nicotinic acetylcholine receptors (AChRs) are activated by
ACh binding to two sites located on different
subunits. The two
subunits, 
and 
, are distinguished
by their interface with
and
subunits. We have characterized the
formation of the ACh binding sites and found, contrary to the current
model, that the sites form at different times and in a set order. The first site forms on 
subunits during the process of
subunit assembly. Our data are consistent with the appearance of this site on 


subunit tetramers soon after the site for the
competitive antagonist
-bungarotoxin has formed and
subunits
have assembled with 

trimers. The second site is located on

subunits and forms after AChR subunits have
assembled into
2

pentamers. By determining the
order in which the ACh binding sites form, we have also identified the
sites in which the
and second
subunits associate during subunit
assembly.
Key words:
protein folding and assembly; acetylcholine;
-bungarotoxin; nicotinic receptors; pharmacology; ligand binding
sites
Copyright © 1998 Society for Neuroscience 0270-6474/98/18155555-10$05.00/0