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BP: Fachverband Biologische Physik

BP 16: Biological Membranes I

BP 16.3: Vortrag

Dienstag, 15. März 2011, 11:00–11:15, ZEU 260

Spatio-temporal modeling of MARCKS protein binding at biological membranes — •Sergio Alonso and Markus Bär — Physikalisch-Technische Bundesanstalt

Proteins inside the cell strongly interact with biological membranes. Depending on the lipid composition of the membrane and the interaction with other proteins, they can spontaneously bind by an electrostatic interaction with acidic phospholipids. We consider a simple model of membrane organization into domains based on a cyclic binding and unbinding of the unfolded MARCKS protein at membranes composed by acidic lipids known as myristo-electrostatic (ME) switch. The function of such proteins is the protection of the phospholipids from hydrolysis by enzymes. Membrane-bound MARCKS may be phosphorylated by Protein kinase C (PKC), which produces the unbinding of the protein. This process is activated by Calcium. Finally, phosphatases dephosphorylate the MARCKS proteins in the cytoplasm, which may bind again at the membrane.

The model describes the formation of membrane domains under nonequilibrium conditions, because the ME switch consumes ATP and leads to non-vanishing currents of proteins. Two main mechanisms of domain formation are obtained: a long-wave instability and a mechanisms based on the bistability of two spatially homogeneous steady-states.

Finally, we compare the predictions of our model with experiments in living cells obtained from the literature and with experimental measurements obtained in vitro.