Membrane remodeling: theoretical principles, structures of protein scaffolds and forces involved

Cellular membranes are dynamic structures that are constantly being remodeled to exert biological functions. This chapter is subdivided into four sections. After a general introduction we review the physical principles underlying the shaping of membranes into curved configurations expressed by the Helfrich model of membrane bending elasticity. We continue by presenting examples of protein scaffolds and their structures that either sense, induce or stabilize curved membranes, such as the BAR domain family of proteins and the ESCRT complexes that catalyze membrane fission. Then, based on specific examples of physical experiments with reconstituted membrane systems, we discuss the factors involved in membrane remodeling, which can lead to membrane constriction and fission. We further describe specific forces exerted on membranes by membrane-bending proteins, molecular motors and the cytoskeleton.