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Title: Phosphoinositide binding inhibits alpha-actinin bundling activity.
Authors: Fraley, TS
Tran, TC
Corgan, AM
Nash, CA
Hao, J
Critchley, DR
Greenwood, JA
First Published: 27-Jun-2003
Citation: J BIOL CHEM, 2003, 278 (26), pp. 24039-24045
Abstract: alpha-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 alpha-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 alpha-actinin function is further characterized. Phosphoinositide binding specificity, determined using a protein-lipid overlay procedure, suggests that alpha-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 alpha-actinin. Phosphoinositide binding inhibited the bundling activity of alpha-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 alpha-actinin mutant with decreased phosphoinositide affinity. We conclude that the interaction of alpha-actinin with phosphoinositides regulates actin stress fibers in the cell by controlling the extent to which microfilaments are bundled.
DOI Link: 10.1074/jbc.M213288200
ISSN: 0021-9258
Type: Journal Article
Appears in Collections:Published Articles, Dept. of Biochemistry

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