University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Wednesday, April 20th 2016
10:10 am:
Biophysics Seminar in 120 PAN
Speaker: Sarah Veatch, University of Michigan
Subject: Phases and fluctuations in biological membranes

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 perturbations which alter both the magnitude of fluctuations in isolated vesicles. Some of these perturbations are also well characterized general anesthetics, and I will present evidence suggesting that some aspects of anesthetic function may be attributed to lipid heterogeneity.

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