Mol Cell Biol. 2011 Jul;31(14):2845-53. doi: 10.1128/MCB.01319-10. Epub 2011 May 16.

Molecular mechanisms of calmodulin action on TRPV5 and modulation by parathyroid hormone.External 2231691f894ba696de1310221b0a0dbbb31a7251e75115c265587c3d9d5f507c

de Groot, T., Kovalevskaya, N. V., Verkaart, S., Schilderink, N., Felici, M., van der Hagen, E. A., Bindels, R. J., Vuister, G. W., Hoenderop, J. G.,
["Nijmegen Center for Molecular Life Sciences, 286 Physiology, Radboud University Nijmegen Medical Center, PO Box 9101, 6500 HB Nijmegen, Netherlands."]
The epithelial Ca(2+) channel transient receptor potential vanilloid 5 (TRPV5) constitutes the apical entry gate for active Ca(2+) reabsorption in the kidney. Ca(2+) influx through TRPV5 induces rapid channel inactivation, preventing excessive Ca(2+) influx. This inactivation is mediated by the last approximately 30 residues of the carboxy (C) terminus of the channel. Since the Ca(2+)-sensing protein calmodulin has been implicated in Ca(2+)-dependent regulation of several TRP channels, the potential role of calmodulin in TRPV5 function was investigated. High-resolution nuclear magnetic resonance (NMR) spectroscopy revealed a Ca(2+)-dependent interaction between calmodulin and a C-terminal fragment of TRPV5 (residues 696 to 729) in which one calmodulin binds two TRPV5 C termini. The TRPV5 residues involved in calmodulin binding were mutated to study the functional consequence of releasing calmodulin from the C terminus. The point mutants TRPV5-W702A and TRPV5-R706E, lacking calmodulin binding, displayed a strongly diminished Ca(2+)-dependent inactivation compared to wild-type TRPV5, as demonstrated by patch clamp analysis. Finally, parathyroid hormone (PTH) induced protein kinase A (PKA)-dependent phosphorylation of residue T709, which diminished calmodulin binding to TRPV5 and thereby enhanced channel open probability. The TRPV5-W702A mutant exhibited a significantly increased channel open probability and was not further stimulated by PTH. Thus, calmodulin negatively modulates TRPV5 activity, which is reversed by PTH-mediated channel phosphorylation.
PMID: 21576356External 2231691f894ba696de1310221b0a0dbbb31a7251e75115c265587c3d9d5f507c
Characterization Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
  Binding region mapping Stoichiometry Affinity (Kd) Reference
TRP channel Interactor
TRP channel Interactor Method Species Region Species Region
TRPV5 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Fusion protein-pull down assay Human 696-729 Not specified Not determined 21576356
TRPV5 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Native-gel electrophoresis Human 696-729 Not specified Not determined 21576356
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
Functional consequence Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
TRP channel Interactor Method Post-translational modification Subcellular trafficking Activity Reference
TRPV5 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Calcium measurement Inhibition 21576356
TRPV5 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Patch clamp Inhibition 21576356
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
TRP / Interactor

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