Bending mechanics and molecular organization in biological membranes

The underlying structure of cell membranes consists of a highly heterogeneous fluid lipid bilayer. Within this milieu, complexes of proteins transiently assemble and dissolve in the performance of the functions of life. The length scales of these coordinated spatial rearrangements can approach the size of the cell, itself, enabling direct visualization in some cases with tantalizing clarity. There has been much interest in the physical driving forces responsible for the assembly of organized structures in cell membranes. Cholesterol-mediated miscibility phase separation within the lipid bilayer has attracted enormous attention over the past decade. This, however, is not the only ordering principle at play. In the following sections, I review recent experimental observations of bending-mediated force transduction and molecular organization in lipid membranes. These results have emerged largely from new experimental methodologies, which are discussed in parallel.