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07:51
Pull-down of Calmodulin-binding Proteins
Published on: January 23, 2012
Aquaporin 6 binds calmodulin in a calcium-dependent manner
Nicole E Rabaud1, Linhua Song, Yiding Wang
1Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
Biochemical and Biophysical Research Communications
|April 2, 2009
Summary
Aquaporin 6 (AQP6) is an anion channel in the kidney. This study found that AQP6 binds to calmodulin, which may reveal its physiological role.
Area of Science:
- Molecular Biology
- Renal Physiology
- Ion Channel Function
Background:
- Aquaporin 6 (AQP6) functions as an anion channel in kidney collecting ducts.
- AQP6 channel activity is regulated by low pH.
- The N-terminus of AQP6 contains a potential calmodulin binding site.
Purpose of the Study:
- To investigate the interaction between Aquaporin 6 (AQP6) and calmodulin.
- To determine if the N-terminal region of AQP6 is responsible for calmodulin binding.
- To characterize the binding affinity between AQP6 and calmodulin.
Main Methods:
- Co-immunoprecipitation assays using AQP6-expressing cell lysates and calmodulin beads.
- Site-directed mutagenesis of the putative N-terminal calmodulin binding site in mouse AQP6.
- Peptide binding assays using dansyl-calmodulin and AQP6 peptides from mouse and human sequences.
Main Results:
- Calmodulin binding to AQP6 was confirmed in the presence of calcium.
- Mutagenesis of the N-terminal site abolished AQP6 calmodulin binding.
- Peptides corresponding to the AQP6 calmodulin binding site exhibited a dissociation constant of approximately 1 µM.
Conclusions:
- Aquaporin 6 (AQP6) directly binds to calmodulin via its N-terminal region.
- This interaction is calcium-dependent and characterized by a moderate affinity.
- Understanding AQP6-calmodulin interaction is crucial for elucidating AQP6's physiological function in the kidney.
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