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AKB: Biologische Physik
AKB 50: Poster Session "Biological Physics"
AKB 50.88: Poster
Freitag, 12. März 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.