Structure/function analysis of the interaction of phosphatidylinositol 4,5-bisphosphate with actin-capping protein: implications for how capping protein binds the actin filament.

ABSTRACT: The heterodimeric actin-capping protein (CP) can be inhibited by polyphosphoinositides, which may be important for actin polymerization at membranes in cells. Here, we have identified a conserved set of basic residues on the surface of CP that are important for the interaction with phosphatidylinositol 4,5-bisphosphate (PIP(2)). Computational docking studies predicted the identity of residues involved in this interaction, and functional and physical assays with site-directed mutants of CP confirmed the prediction. The PIP(2) binding site overlaps with the more important of the two known actin-binding sites of CP. Correspondingly, we observed that loss of PIP(2) binding correlated with loss of actin binding among the mutants. Using TIRF (total internal reflection fluorescence) microscopy, w

SUBMITTER: Kim K 

PROVIDER: S-EPMC2583367 | biostudies-literature | 2007 Feb

REPOSITORIES: biostudies-literature