Interaction of lipid domains originating from differential domain-monolayer contact energy

Abstract

We consider a flat membrane containing monolayer lipid domains separated in the membrane plane. We assume the partial energy of contact between a domain and the underlying monolayer to be different from that between the two regular membrane monolayers. We theoretically analyse the effect of the differential contact energy on the elastic deformations of tilt and splay in the membrane monolayers and the resulting interaction between two domains situated in the apposed monolayers. We demonstrate that the character of this interaction depends on the ratio, η, between the domain rigidity and that of a regular membrane monolayer. For the rigidity ratio smaller than a critical value, η < η* ≈ 3, the domain interaction is predicted to be attractive for all inter-monolayer distances. For large values of the rigidity ratio, η > η*, the interaction is repulsive for small and attractive for large distances with a certain equilibrium inter-domain separation corresponding to a vanishing interaction force. We propose the predicted attractive interaction to contribute towards the domain registration in the membrane plane as observed in most domain-containing membranes.