Probing Role of Cholesterol in Integrin Crosstalk and Complexation of Integrins with GPI-Anchored Urokinase Receptors and Gangliosides using Model Lipid Mixtures

Abstract

Membrane-targeting domains play crucial roles in the association of signaling molecules to the plasma membrane. For most peripheral proteins, the proteinto-membrane interaction is transient; but after proteins dissociate from the membrane they are observed to rebind following a brief excursion in the bulk solution. These membrane hops can have broad implications on protein dynamics. We study the diffusion of membrane-targeting domains using single-molecule tracking in supported lipid bilayers. The ensemble-averaged mean square displacement (MSD) exhibits superdiffusive behavior. However, the time-averaged MSD of individual trajectories is found to be linear with respect to lag time, as in Brownian diffusion. These observations are explained in terms of bulk excursions that introduce jumps with a heavy-tail distribution, rapidly increasing the area explored. Furthermore, this type of motion is characterized by a pronounced scattering in the time-averaged MSD of individual trajectories.