A Toy Model for Active Interfaces

Abstract

A new statistical model predicts the evolving shape of a cellular membrane by accounting for the active feedback between the membrane and attached proteins. A deep concept in contemporary physics is univer-sality, the idea that the behaviors of seemingly different systems are governed by the same un-derlying principles. Consider the edge of a drying coffee stain, the combustion front of a piece of burning pa-per, and the border of an expanding bacterial colony. Zoom out from the microscopic details and one finds that all three cases involve two media separated by a growing interface, whose essential features can be described by a simple equa-tion [1] (see 18 January 2018 Focus story). This universality allows insights learned about one type of interface to be applied to another. But an open question is whether and how this universality extends to the fully nonequilibrium interfaces that prevail in biology, such as growing cellular membranes interacting with proteins. Francesco Cagnetta and colleagues at the University of Edinburgh, UK, have de-veloped a simple and elegant model for a cellular membrane that captures some of this complexity [2]. The new model ac-counts for the bidirectional coupling between the membrane and embedded proteins, predicting the membrane's dynam-ics in ways that might be relevant to cell motion and other biological processes.