This basic science study demonstrates that anionic phospholipids, specifically PIP2, regulate and inhibit the actin-polymerization activity of the capping protein CapZ.
No immediate clinical implications; leaves open whether PIP2 regulation of CapZ can be targeted in cardiovascular disease.
Chicken muscle CapZ, a member of the capping protein family of actin-binding proteins, binds to the barbed end of actin filaments and nucleates actin polymerization. No regulation of the capping protein family has been described. We report that micelles of phosphatidylinositol 4,5-bisphosphate (PIP2) bind to CapZ and completely inhibit its ability to affect actin polymerization as measured by several independent assays. Higher concentrations of other anionic phospholipids also completely inhibit the activity of CapZ. Neutral phospholipids have no effect. Mixed vesicles of PIP2 with phosphatidylcholine or phosphatidylethanolamine also inhibit CapZ, but addition of Triton X-100 both prevents and reverses PIP2's inhibition of CapZ.
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Heiss et al. (1991) studied this question.
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