Title: Phases and fluctuations in biological membranes
Abstract: The thermodynamic properties of plasma membrane lipids play a vital role in many functions that initiate at the mammalian cell surface. Some functions are thought to occur, at least in part, because plasma membrane lipids have a tendency to separate into two distinct liquid phases. We propose that these lipid mediated functions occur because plasma membrane composition is tuned close to a miscibility critical point at physiological temperature. This hypothesis is supported by our observations of micron-sized and dynamic critical composition fluctuations in isolated plasma membranes near room temperature. In this talk, I will discuss our ongoing efforts to probe for the existence and consequences of criticality in the plasma membranes of intact cells. These recent efforts include using quantitative super-resolution fluorescence localization microscopy to monitor the organization of plasma membrane proteins in B cell lymphocytes, both in resting cells and in cells stimulated with multivalent antigen against the B cell receptor. We also have identified a range of membrane perturbations, including n-alcohols, which alter both the magnitude of fluctuations in isolated vesicles. These perturbations of membrane structure are also well characterized general anesthetics, and I will present some preliminary evidence suggesting that some aspects of anesthetic function can be attributed to lipid heterogeneity.
Colloq flyer 4-29 Veatch