Phosphoinositides differentially regulate α-actinin flexibility and function

被引:44
作者
Corgan, AM [1 ]
Singleton, C [1 ]
Santoso, CB [1 ]
Greenwood, JA [1 ]
机构
[1] Oregon State Univ, Dept Biochem & Biophys, Corvallis, OR 97331 USA
关键词
alpha-actinin; actin bundling; cytoskeleton; focal adhesion; phosphoinositide; protein flexibility;
D O I
10.1042/BJ20031124
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
alpha-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 alpha-actinin with actin filaments and integrin receptors. In the present study, we demonstrate that PtdIns(3,4,5)P-3 inhibits and disrupts a-actinin-bundling activity, whereas PtdIns(4,5)P-2 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 alpha-actinin. Both phosphoinositides influenced the extent of proteolysis and the cleavage sites. PtdIns(4,5)P-2 binding decreased the proteolysis of alpha-actinin, suggesting a role in stabilizing the structure of the protein. In contrast, PtdIns(3,4,5)P-3 binding enhanced alpha-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 a-actinin, indicating regulation of structure within both domains. These results support the hypothesis that PtdIns(4,5)P-2 and PtdIns(3,4,5)P-3 differentially regulate alpha-actinin function by modulating the structure and flexibility of the protein.
引用
收藏
页码:1067 / 1072
页数:6
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