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A Lipid-Clustering Mechanism to Trigger Actin Assembly in Cell Extracts

 Hydrate calcium ions bind to PIP2 in a process that leads to their dehydration Filaments in the
cytoplasm that constitute a three dimensional cytoskeleton are formed by
polymerization of the protein actin, which is initiated at distinct sites near the cell
membrane.   Negatively charged lipids in
the membrane corm clusters when intracellular calcium increases, and these
lipid clusters activate proteins that initiate actin assembly.

 

 

 

 

Hydrate calcium
ions bind to PIP2 in a process that leads to their dehydration and strong
binding to phosphomonoesters to ridge between two
lipids.   The multivalent structure of
PIP2 leads to cluster formation in the presence of Ca2 but not other divalent cations to form nan0doamosn
with a finite size near 80 nm.    Such
clusters of PIP2 recruit and activate actin nucleating factors in brain extracts that in turn
initiate actin assembly t site
where the PIP2 is clustered.