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S100B protein stimulates calcineurin activity.
Rodrigo B Leal1, Juliana K Frizzo, Francine Tramontina
1Departamento de Bioquímica, Universidade Federal de Santa Catarina, Brazil.
Neuroreport
|April 13, 2004
Summary
S100B protein enhances calcineurin activity in a calcium-dependent manner. This suggests S100B may regulate cytoskeletal protein phosphorylation in astrocytes.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- S100B is an astrocyte-derived calcium-binding protein.
- It is known to regulate protein phosphorylation by interacting with substrates and protein kinases.
Purpose of the Study:
- To investigate the potential role of S100B in regulating protein phosphatases.
- Specifically, to determine if S100B affects protein phosphatase 2B (calcineurin) activity.
Main Methods:
- Assessed the activity of purified and cytoskeletal calcineurin.
- Utilized varying concentrations of S100B (5-10 microM) in the presence of calcium.
- Employed a specific calcineurin inhibitor and TRTK-12 (an S100B binding inhibitor) to test for specificity.
Main Results:
- S100B significantly increased calcineurin activity in a calcium-dependent manner.
- This enhancement was observed for both purified and cytoskeletal forms of calcineurin.
- The effect was reversed by a calcineurin-specific inhibitor, confirming the interaction, but not by TRTK-12.
Conclusions:
- S100B enhances calcineurin activity, indicating a regulatory role in phosphatase function.
- The co-localization of S100B and calcineurin in astrocytes suggests a functional interaction.
- S100B may influence the phosphorylation state of cytoskeletal proteins via calcineurin modulation.