Regulation of protein mobility in cell membranes: A dynamic corral model

We analyze a two-state stochastic corral model for regulation of protein di ffusion in a cell membrane. This model could mimic control of protein trans port in the membrane by the cytoskeleton. The dynamic corral acts as a gate which when open permits an otherwise trapped protein to escape to a neighb oring corral in the cytoskeletal network. We solve for the escape rate over a wide range of parameters of the model, and compare these results with Mo nte Carte simulations. Upon introducing measured values of the model parame ters for Band 3 in erythrocyte membranes, we are able to estimate the value for one unknown parameter, the average rate at which the corral closes. Th e ratio of calculated closing rate to measured opening rate is roughly 100: 1, consistent with a gating mechanism whereby protein mobility is regulated by dissociation and reassociation of segments of the cytoskeletal network.