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Interactions between neurogranin and calmodulin in vivo
L Prichard1, J C Deloulme, D R Storm
1Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA.
The Journal of Biological Chemistry
|March 13, 1999
Summary
Neurogranin binds calmodulin (CaM) in vivo, supporting its role in regulating CaM availability in neurons. Phosphorylation at serine 36 by protein kinase C (PKC) affects this crucial neurogranin-CaM interaction.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Signaling
Background:
- Neurogranin is a neural-specific protein involved in calmodulin (CaM) binding.
- Protein kinase C (PKC) phosphorylation of neurogranin at serine 36 is mutually exclusive with CaM binding.
- A hypothesis suggests neurogranin concentrates CaM and releases it upon Ca2+ and PKC activation.
Purpose of the Study:
- To establish whether neurogranin interacts with CaM in vivo.
- To identify other proteins that may interact with neurogranin.
- To investigate the role of specific neurogranin residues in CaM binding.
Main Methods:
- Yeast two-hybrid methodology was employed to test for neurogranin-CaM interaction.
- Brain cDNA libraries were screened to identify neurogranin-interacting proteins.
- Site-directed mutagenesis was used to analyze the effect of specific mutations on CaM binding.
Main Results:
- Calmodulin (CaM) was confirmed to bind neurogranin in vivo.
- Calmodulin was the sole neurogranin-interacting protein identified from brain cDNA libraries.
- Mutations at Ile-33, Arg-38, and Ser-36 within the IQ domain significantly affected neurogranin-CaM binding.
Conclusions:
- Calmodulin is the primary protein interacting with neurogranin in vivo.
- The findings support the hypothesis that neurogranin phosphorylation regulates CaM binding.
- Neurogranin's role in concentrating and releasing CaM in neurons is supported by these results.