Molecular mechanisms of calmodulin action on TRPV5 and modulation by parathyroid hormone

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


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 ∼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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Calcium / metabolism
  • Calmodulin / metabolism*
  • Fluorescent Dyes / metabolism
  • Fura-2 / analogs & derivatives
  • Fura-2 / metabolism
  • HEK293 Cells
  • Humans
  • Molecular Sequence Data
  • Nuclear Magnetic Resonance, Biomolecular
  • Parathyroid Hormone / metabolism*
  • Point Mutation
  • Protein Binding
  • TRPV Cation Channels / genetics
  • TRPV Cation Channels / metabolism*


  • Calmodulin
  • Fluorescent Dyes
  • Parathyroid Hormone
  • TRPV Cation Channels
  • TRPV5 protein, human
  • fura-2-am
  • Calcium
  • Fura-2