Bilayer sensor model of erythrocyte shape control.

On the basis of recent studies a model of erythrocyte shape control is presented. This model is based on the assumption that the erythrocyte shape is normally determined by relative surface tensions of the two membrane bilayer surfaces. Our studies have indicated that the erythrocyte shape is preserved and can be restored upon perturbation by an active process. Consequently, it is proposed that in the "bilayer sensor" model the cells "sense" changes in the relative surface tensions, activating a process that balances the tensions so as to create a biconcave disc shape (reaching a new steady state which is observed as long as the perturbant is present). Experimental evidence has indicated that there is a mechanism to sense shape perturbations and two mechanisms to change shape through either crenation or cupping.