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Artificial phosphorylation removes Gelsolin's dependence on calcium
K Takiguchi1, S Yamashiro-Matsumura, F Matsumura
1Department of Molecular Biology and Biochemistry, Rutgers University Piscataway, New Jersey, USA. j46037a@nucc.cc.nagoya-u.ac.jp
Cell Structure and Function
|May 3, 2000
Summary
Phosphorylation of plasma gelsolin by a HeLa cell kinase activates actin binding and filament nucleation independently of calcium. This single modification alters gelsolin function, revealing insights into calcium regulation.
Area of Science:
- Biochemistry
- Cell Biology
- Protein Chemistry
Background:
- Gelsolin is a calcium-regulated actin-binding protein.
- Its activity is crucial for actin dynamics in cells.
Purpose of the Study:
- To investigate the regulatory mechanisms of gelsolin activity.
- To identify how phosphorylation affects gelsolin's interaction with actin.
Main Methods:
- Isolation of a kinase fraction from mitotic HeLa cells.
- Phosphorylation of plasma gelsolin.
- Assessment of gelsolin's actin-severing, capping, and nucleation activities in vitro.
Main Results:
- Plasma gelsolin is phosphorylated at the NH2-terminus by a HeLa cell kinase.
- Phosphorylated gelsolin severs, caps, and nucleates actin filaments without requiring Ca2+.
- The phosphorylation site is distinct from the protein's active regions.
Conclusions:
- Phosphorylation provides a calcium-independent regulatory mechanism for gelsolin.
- Altering electrical interactions via phosphorylation is key to gelsolin's calcium regulation.
- A single modification at a non-core site can significantly alter protein function.