On the role of pore helix in regulation of TRPV5 by extracellular protons

Byung Il Yeh, Joonho Yoon, Chou Long Huang

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


The transient receptor potential channel TRPV5 is localized to the apical membrane of the distal renal tubule and plays an important role in the regulation of transepithelial Ca2+ reabsorption in kidney. We have previously reported that extracellular protons inhibit TRPV5 by binding to glutamate-522 (E522) in the extracellular domain of the channel. We suggested that E522 is an extracellular "pH sensor" and its titration by extracellular protons inhibits TRPV5 via conformational change(s) of the pore helix. We now report that mutation of a pore helix residue glutamate-535 to glutamine (E535Q) enhances the sensitivity of the channel to inhibition by extracellular protons (i.e., shifting the apparent pKa for inhibition by extracellular protons to the more alkaline extracellular pH). The enhancement of extracellular proton-mediated inhibition of E535Q mutant is also dependent on E522. We have also reported that intracellular acidification enhances the sensitivity of TRPV5 to inhibition by extracellular protons. We now find that modulation of the extracellular proton-mediated inhibition by intracellular acidification is preserved in the E535Q mutant. These results provide further support for the idea that pore helix is involved in the regulation of TRPV5 by extracellular protons. Inhibition of TRPV5 by extracellular protons may contribute to hypercalciuria in diseases associated with high acid load.

Original languageEnglish (US)
Pages (from-to)191-198
Number of pages8
JournalJournal of Membrane Biology
Issue number3
StatePublished - Nov 2006


  • Kidney
  • Transepithelial Ca transport
  • Transient receptor potential
  • pH sensing

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology


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