30 September 2011 00:00 hrs.
Membrane protein sequestering by ionic protein-lipid interactions

Geert van den Bogaart, PhD, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany

30-09-2011 00:00:00Europe/AmsterdamMembrane protein sequestering by ionic protein-lipid interactions

Remarks / more information:

Phosphatidylinositol-4,5-bisphosphate (PIP2) is a minor component of the plasma membrane, with only <1% of total lipids in the inner leaflet. Nevertheless, PIP2 is essential for many cellular functions,

including phospholipase-C signaling, cytoskeletal attachment, endocytosis and exocytosis.  Dysregulation of PIP2-levels is implicated in several mental disorders, such as schizophrenia, bipolar disorder and Down's syndrome. Van den Bogaart research is centered around the question:  How can such a minor component of the plasma membrane can be involved in so many functions?

Part of the answer comes from the finding that PIP2 is not uniformly distributed over the plasma membrane. Rather, it is the major lipid component (by far) in small <100nm-sized membrane domains. These domains are formed by simple electrostatic interactions between the anionic PIP2 and cationic regions of membrane proteins. Here, PIP2 acts essentially as a 'salt-bridge' and clusters these membrane proteins together. The clustering of both proteins and PIP2 into membrane domains with dedicated function has clear advantages. Firstly, the high enrichment promotes protein-protein and protein-lipid interactions. Secondly, these compartments form molecular docking sites that facilitate regulation and cellular trafficking.   The finding that membranes can compartmentalize by electrostatic interactions opens up many questions that will be discussed in the presentation .

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