The plasma membrane enveloping mammalian cells is a two-dimensional fluid bilayer consisting primarily of thousands of different types of lipids and proteins. Far from being featureless, it is now well-established that the membrane is "patchy” with spatially organized regions of structure and function, both in terms of lipids and proteins; for an over-view, see Refs. [1-3]. The spatially-extended nature of the membrane "patchiness” together with dynamic membrane processes, due to both thermodynamic fluctuations and non-equilibrium cellular events (such as endo- and exocytosis), provide challenges for theorists and computational scientists alike to develop and simulate quantitative models that seamlessly "funnel” information via coarse-graining from the molecular length and time scales up to the mesoscale.
A. Coarse-graining the static properties of lipid membranes
B. Coarse-graining the dynamic properties of lipid membranes in and out of thermal equilibrium
C. Coarse-graining the description of protein-lipid interactions and protein dynamics
(1) Phase diagrams and phase transition kinetics in multicomponent lipid systems - how do we combine observation and modeling of molecular rearrangements on > 100 nm length scales during domain formation and/or phase transitions?
(2) Coupling between different fluctuating fields (e.g., shape and composition) - how can continuum elastic theories, mean field models and particle-based simulations be combined so as to capture membrane behavior from 1 nm to 10 microns?
(3) Cooperative phenomena in membranes - how do membranes and proteins interact collectively in processes that span multiple length and/or time scales, for example, endocytosis?
(4) Active lipid transport and non-equilibrium membrane processes in live cells - how is energy efficiently deposited into a membrane to drive processes such as raft domain formation, pore formation, vesicle fusion, membrane invagination and protein activity?
(5) Hydrodynamic effects on membrane dynamics and their efficient numerical modeling - when are hydrodynamic effects indispensable in membrane dynamics, and how can their effects be quantitatively captured across scales?
(6) Large-scale membrane remodeling events studied through a hierarchy of scales - how do we connect single-molecule diffusion studies to collective migration of lipid domains or patches?
(7) Cross-coupling between lipids and proteins - Membranes move proteins and proteins reshape membranes: how do we systematically improve the minimal protein models and dynamics currently employed in coarse-grained simulations and parametrize them using atomistic modeling so as to better understand e.g. protein aggregation dynamics?
(8) Connecting single/multiple particle tracking experiments with nanoscale spatial resolution [see, e.g., C Eggeling et al., Nature 457, 1159 (2009)] in live cells to the underlying collective membrane dynamics. What do such experiments reveal about membrane structure and dynamics, and how can theory and simulations be exploited to devise new experimental strategies?