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From Proteopedia
Structure of TRPV1 ion channel in complex with DkTx and RTX determined by single particle electron cryo-microscopy
Structural highlights
Function[TRPV1_RAT] Receptor-activated non-selective calcium permeant cation channel involved in detection of noxious chemical and thermal stimuli. Seems to mediate proton influx and may be involved in intracellular acidosis in nociceptive neurons. May be involved in mediation of inflammatory pain and hyperalgesia. Sensitized by a phosphatidylinositol second messenger system activated by receptor tyrosine kinases, which involves PKC isozymes and PCL. Activation by vanilloids, like capsaicin, and temperatures higher than 42 degrees Celsius, exhibits a time- and Ca(2+)-dependent outward rectification, followed by a long-lasting refractory state. Mild extracellular acidic pH (6.5) potentiates channel activation by noxious heat and vanilloids, whereas acidic conditions (pH <6) directly activate the channel. Can be activated by endogenous compounds, including 12-hydroperoxytetraenoic acid and bradykinin. Acts as ionotropic endocannabinoid receptor with central neuromodulatory effects. Triggers a form of long-term depression (TRPV1-LTD) mediated by the endocannabinoid anandamine in the hippocampus and nucleus accumbens by affecting AMPA receptors endocytosis.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] Publication Abstract from PubMedTransient receptor potential (TRP) channels are polymodal signal detectors that respond to a wide range of physical and chemical stimuli. Elucidating how these channels integrate and convert physiological signals into channel opening is essential to understanding how they regulate cell excitability under normal and pathophysiological conditions. Here we exploit pharmacological probes (a peptide toxin and small vanilloid agonists) to determine structures of two activated states of the capsaicin receptor, TRPV1. A domain (consisting of transmembrane segments 1-4) that moves during activation of voltage-gated channels remains stationary in TRPV1, highlighting differences in gating mechanisms for these structurally related channel superfamilies. TRPV1 opening is associated with major structural rearrangements in the outer pore, including the pore helix and selectivity filter, as well as pronounced dilation of a hydrophobic constriction at the lower gate, suggesting a dual gating mechanism. Allosteric coupling between upper and lower gates may account for rich physiological modulation exhibited by TRPV1 and other TRP channels. TRPV1 structures in distinct conformations reveal activation mechanisms.,Cao E, Liao M, Cheng Y, Julius D Nature. 2013 Dec 5;504(7478):113-8. doi: 10.1038/nature12823. PMID:24305161[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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