Molecular sorting on a fluctuating membrane

TL;DR

This paper investigates how Casimir-like forces in fluctuating membranes influence molecular sorting, revealing that these entropic forces enhance domain formation and molecular capture, especially when direct interactions are weak.

Contribution

It introduces the role of Casimir-like forces in membrane sorting, combining theoretical and simulation approaches to show their impact on domain formation and efficiency.

Findings

Casimir-like forces reduce the critical radius for domain formation

These forces facilitate molecular capture within sorting domains

Membrane rigidity controls sorting efficiency

Abstract

Molecular sorting in biological membranes is essential for proper cellular function. It also plays a crucial role in the budding of enveloped viruses from host cells. We recently proposed that this process is driven by phase separation, where the formation and growth of sorting domains depend primarily on direct intermolecular interactions. In addition to these, Casimir-like forces -- arising from entropic effects in fluctuating membranes -- may also play a significant role in the molecular distillation process. Here, using a combination of theoretical analysis and numerical simulations, we explore how Casimir-like forces between rigid membrane inclusions contribute to sorting, particularly in the biologically relevant regime where direct intermolecular interactions are weak. Our results show that these forces enhance molecular distillation by reducing the critical radius for the formation of new sorting domains and facilitating the capture of molecules within these domains. We identify the relative rigidity of the membrane and supermolecular domains as a key parameter controlling molecular sorting efficiency, offering new insights into the physical principles underlying molecular sorting in biological systems.