Random pinning limits the size of membrane adhesion domains

TL;DR

This paper demonstrates that random pinning due to membrane proteins prevents large-scale adhesion domain formation, fundamentally altering membrane adhesion behavior predicted by classical models.

Contribution

The study introduces the concept that membrane pinning acts as a random-field disorder, preventing macroscopic adhesion domains, supported by analytical and Monte Carlo simulation evidence.

Findings

Random pinning induces quenched disorder in membranes.

Macroscopic adhesion domains are suppressed by random-field effects.

Monte Carlo simulations confirm the theoretical predictions.

Abstract

Theoretical models describing specific adhesion of membranes predict (for certain parameters) a macroscopic phase separation of bonds into adhesion domains. We show that this behavior is fundamentally altered if the membrane is pinned randomly due to, e.g., proteins that anchor the membrane to the cytoskeleton. Perturbations which locally restrict membrane height fluctuations induce quenched disorder of the random-field type. This rigorously prevents the formation of macroscopic adhesion domains following the Imry-Ma argument [Y. Imry and S. K. Ma, Phys. Rev. Lett. 35, 1399 (1975)]. Our prediction of random-field disorder follows from analytical calculations, and is strikingly confirmed in large-scale Monte Carlo simulations. These simulations are based on an efficient composite Monte Carlo move, whereby membrane height and bond degrees of freedom are updated simultaneously in a single move. The application of this move should prove rewarding for other systems also.