Phosphoinositide Binding Inhibits α-Actinin Bundling Activity*
By Tamara S. Fraley, Thuan C. Tran, Anne Marie Corgan, Coral A. Nash, Jie Hao, D. Critchley, J. A. Greenwood. Journal of Biological Chemistry, 2003
86 citations recorded by the source corpus.
α-Actinin is an abundant actin-bundling and adhesion protein that directly links actin filaments to integrin receptors. Previously, in platelet-derived growth factor-treated fibroblasts, we demonstrated that phosphoinositides bind to α-actinin, regulating its localization (Greenwood, J. A., Theibert, A. B., Prestwich, G. D., and Murphy-Ullrich, J. E. (2000) J. Cell Biol. 150, 627– 642). In this study, phosphoinositide binding and regulation of α-actinin function is further characterized. Phosphoinositide binding specificity, determined using a protein-lipid overlay procedure, suggests that α-actinin interacts with phosphates on the 4th and 5th position of the inositol head group. Binding assays and mutational analyses demonstrate that phosphoinositides bind to the calponin homology domain 2 of α-actinin. Phosphoinositide binding inhibited the bundling activity of α-actinin by blocking the interaction of the actin-binding domain with actin filaments. Consistent with these results, excessive bundling of actin filaments was observed in fibroblasts expressing an α-actinin mutant with decreased phosphoinositide affinity. We conclude that the interaction of α-actinin with phosphoinositides regulates actin stress fibers in the cell by controlling the extent to which microfilaments are bundled.
Subfields: Cell Biology, Genetics
View Paper: https://www.semanticscholar.org/paper/8e2e29b89e2fdf9cd4182425c04757a102ea1e24
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In Genetics
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- A gene for speed? The evolution and function of α‐actinin‐3 (2004, background): “PIP2 increases the affinity of aactinin for titin((49)) and inhibits binding to CapZ,((29)) while there are contradictory reports on its effects on actin binding.((50,51)) The PIP2-binding site of a-actinin is located between the ABD and the first spectrin-like repeat and bears recognisable”