title: Hill coefficients of a polymodal Monod-Wyman-Changeux model for ion channel gating.
abstract: Allosteric transitions of ion channels can be driven by multiple sources of free energies. One class of model for describing such transitions is the multistimulus Monod-Wyman-Changeux model, in which each stimulus interacts with a specific sensor on the protein and activation of the sensor is allosterically coupled to conformational changes of the protein. In general, when a protein is stressed by multiple stimuli, one stimulus can influence the response to another, which can result in both a shift of the midpoint of the dose-response curve and a change of the slope of the curve. Here I show that, for a Monod-Wyman-Changeux model with independent sensors, the different dose-response curves of open probability for one stimulus have the same slope at the same agonist concentration. In the other words, the slope of the dose-response curve for one stimulus is an intrinsic property of the sensors for that stimulus; it is independent of other stimuli or their sensor properties. As the dose-response curve for many receptors can be fit to a Boltzmann or Hill equation, this property provides a practical, usable test for applicability of such models.
authors.affiliation: Department of Physiology and Biophysical Sciences, State University of New York at Buffalo, Buffalo, New York, USA. qin@buffalo.edu
authors.forename: Feng
authors.initials: F
authors.lastname: Qin
mesh_terms: D000818:Animals; D015640:Ion Channel Gating / Q000502:physiology*; D008954:Models, Biological