Thursday, October 13, 2011
Towards a Mechanistic Understanding of Cell Membranes
Caltech and USC
We provide an overview of recent work on the description of biological cell membranes in terms of coarse-grained physical theories. Any such mechanistic understanding of cell membranes requires information about the molecular properties of membrane components. It has been proposed that polyhedral bilayer vesicles may offer a route towards a more comprehensive knowledge of the structure of membrane components and the energetics of their interactions. Motivated by these experiments, we first study the elastic bending energy of polyhedral bilayer vesicles to determine energetically favorable polyhedral symmetries, and to propose strategies for the control of the shape and size of bilayer polyhedra. Second, inspired by known membrane protein structures, we carry out a systematic study of how protein symmetry affects the deformation profile of the surrounding lipid bilayer membrane. For the prototypical case of mechanosensitive ion channels, our calculations imply that changes in the symmetry of membrane deformations can substantially alter the energetic competition between different conformational states and affect the channel gating characteristics. Finally, as a case study for the collective behavior exhibited by many membrane proteins, we consider the clustering of synaptic receptor molecules localized in neural cell membranes. We use a combined experimental and theoretical approach to develop a quantitative description of synaptic receptor domains in terms of a reaction-diffusion model in which protein concentrations are represented by continuous fields. We find that—contrary to what has classically been assumed—interactions between only receptor and scaffold molecules, together with the rapid diffusion of receptors on the cell membrane, can explain the formation, stability, and characteristic size of synaptic receptor domains.
Refreshments at 11:00 AM. Seminar begins at 11:10 AM.
Building 8, Room 241
For further information, please call (909) 869-4014