Postsynaptic signal transduction plays a crucial role in brain functioning. It consists of molecular signalling cascades, initiated at the postsynaptic membrane, where hundreds of different bio - macromolecules are diffusing and interacting. To date, the spatio-temporal correlations between the various types of membrane proteins and lipids are still largely unexplored even in the initial stage of signalling. We have developed a mesoscale protein - membrane - cytosol model of initial - stage postsynaptic signalling which we analyze using multiparticle collision dynamics (MPC) and Langevin dynamics simulation methods. Realistic input parameters are obtained from quasi - atomistic simulations performed in our collaborating group at INM-9 (V. Calandrini / P. Carloni). This allows to bridge the gap between molecular and mesoscale length and time scales. We currently explore how effective interactions, diffusion and possible clustering (oligomer formation) of specific GPCR proteins are influenced by the membrane and surrounding cytosol fluid.

In a related project, using MPC simulations and theory we study the phase behavior and dynamics of interacting globular proteins confined to quasi-two-dimensional (Q2D) motion along a planar fluid interface embedded in a bulk fluid. We consider proteins with competing short - range attractive and long - range repulsive interactions which exhibit a plethora of equilibrium and non - equilibrium cluster phases. The interplay of Q2D protein motion and solvent - mediated hydrodynamic interactions gives rise to peculiar effects such as anomaloulsly enhanced collective diffusion down a concentration gradient.