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Actopaxin interacts with TESK1 to regulate cell spreading on fibronectin
David P LaLonde1, Michael C Brown, Brian P Bouverat
1Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA.
The Journal of Biological Chemistry
|April 9, 2005
Summary
Actopaxin directly binds testicular protein kinase 1 (TESK1), inhibiting its activity and regulating cell spreading. This interaction, influenced by fibronectin adhesion and actopaxin phosphorylation, controls cofilin phosphorylation and cell motility.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Actopaxin is a focal adhesion protein crucial for cell adhesion, spreading, and motility.
- Testicular protein kinase 1 (TESK1) regulates cell spreading and focal adhesion formation by phosphorylating cofilin.
Purpose of the Study:
- To identify and characterize the interaction between actopaxin and TESK1.
- To elucidate the functional consequences of this interaction on cellular processes and TESK1 activity.
Main Methods:
- Direct binding assays to confirm the interaction between actopaxin and TESK1.
- Mapping of binding sites to the carboxyl termini of both proteins.
- In vitro kinase assays to assess TESK1 activity in the presence of actopaxin.
Main Results:
- A direct interaction between actopaxin and TESK1 was identified, localized to their carboxyl termini.
- The actopaxin-TESK1 association is negatively regulated by fibronectin adhesion and impaired in a phosphomimetic actopaxin mutant.
- Binding of actopaxin inhibits TESK1 kinase activity, affecting cofilin phosphorylation and cell spreading.
Conclusions:
- Actopaxin directly binds and inhibits TESK1 kinase activity.
- This interaction is regulated by cell adhesion and actopaxin phosphorylation.
- The actopaxin-TESK1 complex plays a role in regulating cellular spreading on fibronectin through cofilin phosphorylation.