Adhesion-induced phase separation of multiple species of membrane junctions

TL;DR

This paper develops a theoretical model explaining how membrane adhesion and physical properties of junctions induce phase separation into distinct domains, influenced by height differences, rigidity, elasticity, and thermal fluctuations.

Contribution

The study introduces a comprehensive theory integrating multiple mechanisms driving membrane junction phase separation, highlighting the roles of junction height, rigidity, elasticity, and thermal fluctuations.

Findings

Height difference is the main driver of junction separation.

Softer junctions tend to aggregate and dominate.

Membrane elasticity and fluctuations induce non-local interactions.

Abstract

A theory is presented for the membrane junction separation induced by the adhesion between two biomimetic membranes that contain two different types of anchored junctions (receptor/ligand complexes). The analysis shows that several mechanisms contribute to the membrane junction separation. These mechanisms include (i) the height difference between type-1 and type-2 junctions is the main factor which drives the junction separation, (ii) when type-1 and type-2 junctions have different rigidities against stretch and compression, the ``softer'' junctions are the ``favored'' species, and the aggregation of the softer junction can occur, (iii) the elasticity of the membranes mediates a non-local interaction between the junctions, (iv) the thermally activated shape fluctuations of the membranes also contribute to the junction separation by inducing another non-local interaction between the junctions and renormalizing the binding energy of the junctions. The combined effect of these mechanisms is that when junction separation occurs, the system separates into two domains with different relative and total junction densities.