Conformational dynamics of the alphaM3 transmembrane helix during acetylcholine receptor channel gating.

ABSTRACT: Muscle acetylcholine receptors are synaptic ion channels that "gate" between closed- and open-channel conformations. We used Phi-value analysis to probe the transition state of the diliganded gating reaction with regard to residues in the M3, membrane-spanning helix of the muscle acetylcholine receptor alpha-subunit. Phi (a fraction between 1 and 0) parameterizes the extent to which a mutation changes the opening versus the closing rate constant and, for a linear reaction mechanism, the higher the Phi-value, the "earlier" the gating motion. In the upper half of alphaM3 the gating motions of all five tested residues were temporally correlated (Phi approximately 0.30) and serve to link structural changes occurring at the middle of the M2, pore-lining helix with those occurring at the interfa

SUBMITTER: Cadugan DJ 

PROVIDER: S-EPMC1913136 | biostudies-literature | 2007 Aug

REPOSITORIES: biostudies-literature