Energetics of adhesion cluster formation in the context of biological membranes.

The orchestration of cellular adhesion is an intricate process that involves a multitude of specialized proteins but at the same time follows a simple physical plan. It is still not totally known why cells create clusters of bonds to adhere on a substrate. Besides experimental methods to study cellular adhesion there exist several different theoretical models to describe the stability of focal adhesion clusters. The model proposed in this work makes it possible to understand the formation of adhesion bond clusters. It explains the emergence of a long-range bond-bond attraction that originates from the finite membrane elasticity as the driving force of cluster growth. In combination with a thermally driven bond disintegration such a model will eventually be able to explain the kinetic stability of finite size bond clusters. The model extends conventional two-state models where bonds are either open or closed by introducing a rich scenario of metastable states associated with hysteretic behavior in the bond closure and rupture dynamics.