1998 Fiscal Year Final Research Report Summary
The Regulational Mechanism for the Formation of Cadherin-Catenin Complex in alpha-Catenin Level
Project/Area Number |
09670136
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Single-year Grants |
Section | 一般 |
Research Field |
General medical chemistry
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Research Institution | Kagoshima University |
Principal Investigator |
OBAMA Hiroya Faculty of Medicine Kagoshima University, Research Associate, 医学部, 助手 (70264405)
|
Project Period (FY) |
1997 – 1998
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Keywords | cadherin / alpha-catenin / beta-catenin / plakoglobin / actin / phosphatidyl-inositol 4,5-bisphosphate |
Research Abstract |
alpha-Catenin is an important molecule for the adhesive function of cadherins, which mainly function at adherence junction through the homophilic mechanism. We have reported that alpha-catenin binds with beta-catenin or plakoglobin by its the amino-terminal region. In this study we examined firstly whether alpha-catenin can directly bind to the cytoskeleton, actin filament. Various regions of alpha-catenin were expressed as the fusion protein with glutathione-S-transferase (GST). GST/alpha-catenin fusion proteins were incubated with actin filaments. The binding ability of GST/alpha-catenin fusion proteins to actin filament was assessed by co-sedimentation assay. The assay revealed that the carboxyl-terminal region bound most strongly to actin filament. This carboxyl-terminal region was also found to be able to interact with the central region of alpha-catenin. As the affinity of alpha-catenin for the cytoskeleton is weaker than that of the carboxyl-terminal region of alpha-catenin, the interaction between central and carboxyl regions might interfere the access of the carboxyl-terminal region to actin filament. Phosphatidyl-inositol 4,5-bisphosphate (PIP2) is known to regulate functions of many actin binding proteins, for example, alpha-actinin, vinculin, gelsolin and profilin. As the next project, we checked the interaction between PIP2 and alpha-catenin. The binding assay revealed that alpha-catenin bound most strongly to PIP2 in tested five lipids, and that the carboxyl-terminal region was important for this interaction. The binding ability of alpha-catenin to actin filament might be modulated by PlP2 associated with conformational change of alpha-catenin. These results mentioned above suggest that the carboxyl-terminal region of alpha-catenin may have multi-function, actin-binding, PIP2-binding and inter-domains interaction. These functions possibly regulate the link between cadherin molecules and cytoskeleton.
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