Budding Transition of Asymmetric Two-component Lipid Domains

TL;DR

This paper presents a model for the budding transition in asymmetric lipid domains, revealing complex phase behavior and coexistence of different membrane morphologies driven by composition and curvature coupling.

Contribution

It introduces a mean-field model that captures the thermodynamics and morphology of asymmetric lipid domains, including phase diagrams with multiple coexisting states.

Findings

Identification of phase diagrams with budded, dimpled, and flat states.

Prediction of coexistence regions between different domain morphologies.

Analysis of how leaflet composition influences membrane phase behavior.

Abstract

We propose a model that accounts for the budding transition of asymmetric two-component lipid domains, where the two monolayers (leaflets) have different average compositions controlled by independent chemical potentials. Assuming a coupling between the local curvature and local lipid composition in each of the leaflets, we discuss the morphology and thermodynamic behavior of asymmetric lipid domains. The membrane free-energy contains three contributions: the bending energy, the line tension, and a Landau free-energy for a lateral phase separation. Within a mean-field treatment, we obtain various phase diagrams containing fully budded, dimpled, and flat states as a function of the two leaflet compositions. The global phase behavior is analyzed, and depending on system parameters, the phase diagrams include one-phase, two-phase and three-phase regions. In particular, we predict various phase coexistence regions between different morphologies of domains, which may be observed in multi-component membranes or vesicles.