Vesicle budding induced by binding of curvature-inducing proteins

TL;DR

This study uses mean-field theory to analyze how protein binding induces vesicle budding, revealing phase transitions and effects of various parameters on bud formation and size.

Contribution

It introduces a simple, adaptable scheme to model protein-induced vesicle budding, including effects of interactions, membrane properties, and curvature sensing.

Findings

First-order transition between large and small buds at high curvature or rigidity

Coexistence of different bud states near transition point

Effects of inter-protein interactions and membrane elasticity on budding behavior

Abstract

Vesicle budding induced by protein binding that generates an isotropic spontaneous curvature is studied using a mean-field theory. Many spherical buds are formed via protein binding. As the binding chemical potential increases, the proteins first bind to the buds and then to the remainder of the vesicle. For a high spontaneous curvature and/or high bending rigidity of the bound membrane, it is found that a first-order transition occurs between a small number of large buds and a large number of small buds. These two states coexist around the transition point. The proposed scheme is simple and easily applicable to many interaction types, so we investigate the effects of inter-protein interactions, the protein-insertion-induced changes in area, the variation of the saddle-splay-modulus, and the area-difference-elasticity energy. The differences in the preferred curvatures for curvature sensing and generation are also clarified.