Adhesion of membranes via receptor-ligand complexes: Domain formation, binding cooperativity, and active processes

TL;DR

This review discusses how membrane-anchored receptor-ligand interactions facilitate cell adhesion, emphasizing the roles of membrane elasticity, thermal fluctuations, and active processes in domain formation and cooperative binding.

Contribution

It provides a theoretical framework modeling membrane adhesion as elastic sheets with receptor-ligand complexes, highlighting the impact of thermal roughness and active processes on domain formation.

Findings

Thermal membrane roughness promotes cooperative receptor-ligand binding.

Receptor domains result from a combination of spontaneous and active processes.

Effective adhesion potentials depend on molecule concentrations and binding energies.

Abstract

Cell membranes interact via anchored receptor and ligand molecules. Central questions on cell adhesion concern the binding affinity of these membrane-anchored molecules, the mechanisms leading to the receptor-ligand domains observed during adhesion, and the role of cytoskeletal and other active processes. In this review, these questions are addressed from a theoretical perspective. We focus on models in which the membranes are described as elastic sheets, and the receptors and ligands as anchored molecules. In these models, the thermal membrane roughness on the nanometer scale leads to a cooperative binding of anchored receptor and ligand molecules, since the receptor-ligand binding smoothens out the membranes and facilitates the formation of additional bonds. Patterns of receptor domains observed in Monte Carlo simulations point towards a joint role of spontaneous and active processes in cell adhesion. The interactions mediated by the receptors and ligand molecules can be characterized by effective membrane adhesion potentials that depend on the concentrations and binding energies of the molecules.