Mechanics of non-planar membranes with force-dipole activity

TL;DR

This paper develops an analytical framework to understand how active membrane proteins, modeled as force dipoles, influence the mechanical properties and interactions of non-planar fluid membranes.

Contribution

It introduces a moment expansion approach to incorporate active force distributions into membrane mechanics, revealing effects on tension, bending, and protein interactions.

Findings

Active proteins modify membrane tension and bending moments.

Force dipoles induce hydrodynamic attraction between proteins.

Analytic expression for activity-modified force-balance derived.

Abstract

A study is made of how active membrane proteins can modify the long wavelength mechanics of fluid membranes. The activity of the proteins is modelled as disturbing the protein surroundings through non-local force distributions of which a force-dipole distribution is the simplest example. An analytic expression describing how the activity modifies the force-balance equation for the membrane surface is obtained in the form of a moment expansion of the force distribution. This expression allows for further studies of the consequences of the activity for non-planar membranes. In particular the active contributions to mechanical properties such as tension and bending moments become apparent. It is also explained how the activity can induce a hydrodynamic attraction between the active proteins in the membrane.