Membrane Fluctuations Destabilize Clathrin Protein Lattice Order.

摘要

The authors develop a theoretical model of a clathrin protein lattice on a exible cell membrane. The clathrin subunit is modeled as a three-legged pinwheel with elastic deformation modes and inter-subunit binding interactions. The pinwheels are constrained to lie on the surface of an elastic sheet that opposes bending deformation and is subjected to tension. Through Monte Carlo simulations, we predict the equilibrium phase behavior of clathrin lattices at various levels of tension. High membrane tensions, which correspond to suppressed membrane fluctuations, tend to stabilize large, at crystalline structures similar to 'plaques' that have been observed in vivo on cell membranes that are adhered to rigid surfaces. Low tensions, on the other hand, give rise to disordered, defect-ridden lattices that behave in a fluid-like manner. The principles of two-dimensional melting theory are applied to our model system to further clarify how high tensions can stabilize crystalline order on flexible membranes. These results demonstrate the importance of environmental physical cues in dictating the collective behavior of self-assembled protein structures.