α-Actinin is a cell-adhesion and cytoskeletal protein that bundles actin microfilaments and links these filaments directly to integrin-adhesion receptors. Phosphoinositides bind to and regulate the interaction of α-actinin with actin filaments and integrin receptors. In the present study, we demonstrate that PtdIns(3,4,5)P3 inhibits and disrupts α-actinin-bundling activity, whereas PtdIns(4,5)P2 can only inhibit activity. In addition, a protease-sensitivity assay was developed to examine the flexibility of the linker region between the actin-binding domain and the spectrin repeats of α-actinin. Both phosphoinositides influenced the extent of proteolysis and the cleavage sites. PtdIns(4,5)P2 binding decreased the proteolysis of α-actinin, suggesting a role in stabilizing the structure of the protein. In contrast, PtdIns(3,4,5)P3 binding enhanced α-actinin proteolysis, indicating an increase in the flexibility of the protein. Furthermore, phosphoinositide binding influenced the proteolysis of the N- and C-terminal domains of α-actinin, indicating regulation of structure within both domains. These results support the hypothesis that PtdIns(4,5)P2 and PtdIns(3,4,5)P3 differentially regulate α-actinin function by modulating the structure and flexibility of the protein.
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March 2004
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Research Article|
March 15 2004
Phosphoinositides differentially regulate alpha-actinin flexibility and function
Anne Marie CORGAN;
Anne Marie CORGAN
Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, U.S.A.
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CoreyAyne SINGLETON;
CoreyAyne SINGLETON
Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, U.S.A.
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Cynthia B. SANTOSO;
Cynthia B. SANTOSO
Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, U.S.A.
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Jeffrey A. GREENWOOD
Jeffrey A. GREENWOOD
1
Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, U.S.A.
1To whom correspondence should be addressed (e-mail jeffrey.greenwood@orst.edu).
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Publisher: Portland Press Ltd
Received:
July 24 2003
Revision Received:
December 08 2003
Accepted:
December 12 2003
Accepted Manuscript online:
December 12 2003
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2004
2004
Biochem J (2004) 378 (3): 1067–1072.
Article history
Received:
July 24 2003
Revision Received:
December 08 2003
Accepted:
December 12 2003
Accepted Manuscript online:
December 12 2003
Citation
Anne Marie CORGAN, CoreyAyne SINGLETON, Cynthia B. SANTOSO, Jeffrey A. GREENWOOD; Phosphoinositides differentially regulate alpha-actinin flexibility and function. Biochem J 15 March 2004; 378 (3): 1067–1072. doi: https://doi.org/10.1042/bj20031124
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