Phosphoinositide binding inhibits α-actinin bundling activity

Tamara S. Fraley, Thuan C. Tran, Anne Marie Corgan, Coral A. Nash, Jie Hao, David R. Critchley, Jeffrey A. Greenwood

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)24039-24045
Number of pages7
JournalJournal of Biological Chemistry
Issue number26
StatePublished - Jul 27 2003
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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