title: The pain receptor TRPV1 displays agonist-dependent activation stoichiometry.
abstract: The receptor channel TRPV1 (Transient Receptor Potential Vanilloid 1) is expressed by primary afferent sensory neurons of the pain pathway, where it functions as a sensor of noxious heat and various chemicals, including eicosanoids, capsaicin, protons and peptide toxins. Comprised of four identical subunits that organize into a non-selective cationic permeable channel, this receptor has a variety of binding sites responsible for detecting their respective agonists. Although its physiological role as a chemosensor has been described in detail, the stoichiometry of TRPV1 activation by its different ligands remains unknown. Here, we combined the use of concatemeric constructs harboring mutated binding sites with patch-clamp recordings in order to determine the stoichiometry for TRPV1 activation through the vanilloid binding site and the outer-pore domain by capsaicin and protons, respectively. We show that, while a single capsaicin-bound subunit was sufficient to achieve a maximal open-channel lifetime, all four proton-binding sites were required. Thus, our results demonstrate a distinct stoichiometry of TRPV1 activation through two of its different agonist-binding domains.
authors.affiliation: The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
authors.forename: Adina
authors.initials: A
authors.lastname: Hazan
authors.affiliation: The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.affiliation: The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
authors.forename: Henry
authors.initials: H
authors.lastname: Matzner
authors.affiliation: The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
authors.forename: Avi
authors.initials: A
authors.lastname: Priel
mesh_terms: D000818:Animals; D001665:Binding Sites; D002211:Capsaicin / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D021122:Protein Subunits / Q000378:metabolism; D011522:Protons; D051381:Rats; D050916:TRPV Cation Channels / Q000819:agonists* / Q000378:metabolism
chemical_list: D021122:Protein Subunits; D011522:Protons; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D002211:Capsaicin