The goal of this proposal is to investigate the nature of the transition state of the allosteric conformational change that controls the gating reaction of the acetylcholine receptor, an ion channel that opens (i.e., becomes ion-permeable) in response to the neurotransmitter acetylcholine. The transition state for the gating reaction may be a unique state that represents a saddle point on a free energy surface describing the reaction, like many transition states of reactions of small organic molecules. Alternatively, the gating reaction may proceed through a transition state ensemble composed of many closely spaced microstates, similar to the transition regions of some protein folding reactions. Linear free energy relationship analysis of multiple reaction coordinates will allow these possibilities to be distinguished. Measurement of single-channel currents via patch-clamp electrophysiology will allow determination of microscopic rate constants and equilibrium constants for gating. Site- directed mutagenesis, variation of ligand occupancy, and control of transmembrane voltage will be used to perturb the gating equilibrium for the linear free energy relationship analysis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32GM063460-02
Application #
6520540
Study Section
Special Emphasis Panel (ZRG1-MDCN-1 (20))
Program Officer
Cassatt, James
Project Start
2001-04-09
Project End
2002-06-30
Budget Start
2002-04-09
Budget End
2002-06-30
Support Year
2
Fiscal Year
2002
Total Cost
$12,391
Indirect Cost
Name
State University of New York at Buffalo
Department
Physiology
Type
Schools of Medicine
DUNS #
038633251
City
Buffalo
State
NY
Country
United States
Zip Code
14260
Jennings, Laura D; Bohon, Jen; Chance, Mark R et al. (2008) The ClpP N-terminus coordinates substrate access with protease active site reactivity. Biochemistry 47:11031-40
Mitra, Ananya; Tascione, Richard; Auerbach, Anthony et al. (2005) Plasticity of acetylcholine receptor gating motions via rate-energy relationships. Biophys J 89:3071-8