title: Functional anatomy of an allosteric protein.
abstract: Synaptic receptors are allosteric proteins that switch on and off to regulate cell signalling. Here, we use single-channel electrophysiology to measure and map energy changes in the gating conformational change of a nicotinic acetylcholine receptor. Two separated regions in the α-subunits--the transmitter-binding sites and αM2-αM3 linkers in the membrane domain--have the highest ϕ-values (change conformation the earliest), followed by the extracellular domain, most of the membrane domain and the gate. Large gating-energy changes occur at the transmitter-binding sites, α-subunit interfaces, the αM1 helix and the gate. We hypothesize that rearrangements of the linkers trigger the global allosteric transition, and that the hydrophobic gate unlocks in three steps. The mostly local character of side-chain energy changes and the similarly high ϕ-values of separated domains, both with and without ligands, suggest that gating is not strictly a mechanical process initiated by the affinity change for the agonist.
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA.
authors.forename: Prasad
authors.initials: P
authors.lastname: Purohit
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA.
authors.forename: Shaweta
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA.
authors.forename: Snehal
authors.initials: S
authors.lastname: Jadey
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Auerbach
mesh_terms: D000465:Algorithms; D000495:Allosteric Site; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004594:Electrophysiology; D057809:HEK293 Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D011978:Receptors, Nicotinic / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D008024:Ligands; D011978:Receptors, Nicotinic