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Regensburg 2004 – scientific programme

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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.88: Poster

Friday, March 12, 2004, 10:30–13:00, B

Dynamics of Lipid and Protein Domains in Biomembranes — •Karin John and Markus Bär — Max-Planck-Institute für die Physik komplexer Systeme, Nöthnitzer Strasse 38, D-01187 Dresden

Acidic lipids such as PIP2 and PIP3 are thought to elicit localized responses, e.g. for remodeling the cytoskeleton in response to external stimuli. We consider a mechanism that accounts for a nonrandom distribution of acidic lipids in the plasma membrane: electrostatic sequestration by basic proteins such as GMC (MARCKS, CAP23, GAP43) proteins. Our strategy is to incorporate the different properties of GMC proteins into a reaction-diffusion model:
1. GMC proteins are cytosolic proteins. Membrane association depends on a basic effector domain, which interacts with acidic lipids in the membrane and can lead to the formation of domains enriched in acidic lipids and GMC.
2. GMC proteins are probably integrators of PKC and Ca2+ signalling pathways. Upon phosphorylation of residues within the basic effector domain by a protein kinase C or interaction with Ca++/calmodulin GMC proteins translocate from the membrane into the cytosol. Upon dephosphorylation or a decrease in cytosolic Ca++ GMC proteins reassociates with the membrane. This cycle is called myristoyl-electrostatic switch (ME-switch).
The resulting model reveals different mechanism of phase separation acting on different length scales, namely phase separation driven by protein-lipid interaction as well as phase separation due to enzymatic activity. In addition, we find also oscillatory behavior and traveling domains.

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