3sui
From Proteopedia
Crystal structure of ca2+-calmodulin in complex with a trpv1 c-terminal peptide
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) vanilloid 1 (TRPV1) is a molecular pain receptor belonging to the TRP superfamily of nonselective cation channels. As a polymodal receptor, TRPV1 responds to heat and a wide range of chemical stimuli. The influx of calcium after channel activation serves as a negative feedback mechanism leading to TRPV1 desensitization. The cellular calcium sensor calmodulin (CaM) likely participates in the desensitization of TRPV1. Two CaM-binding sites are identified in TRPV1: the N-terminal ankyrin repeat domain (ARD) and a short distal C-terminal (CT) segment. Here, we present the crystal structure of calcium-bound CaM (Ca(2+)-CaM) in complex with the TRPV1-CT segment, determined to 1.95-A resolution. The two lobes of Ca(2+)-CaM wrap around a helical TRPV1-CT segment in an antiparallel orientation, and two hydrophobic anchors, W787 and L796, contact the C-lobe and N-lobe of Ca(2+)-CaM, respectively. This structure is similar to canonical Ca(2+)-CaM-peptide complexes, although TRPV1 contains no classical CaM recognition sequence motif. Using structural and mutational studies, we established the TRPV1 C terminus as a high affinity Ca(2+)-CaM-binding site in both the isolated TRPV1 C terminus and in full-length TRPV1. Although a ternary complex of CaM, TRPV1-ARD, and TRPV1-CT had previously been postulated, we found no biochemical evidence of such a complex. In electrophysiology studies, mutation of the Ca(2+)-CaM-binding site on TRPV1-ARD abolished desensitization in response to repeated application of capsaicin, whereas mutation of the Ca(2+)-CaM-binding site in TRPV1-CT led to a more subtle phenotype of slowed and reduced TRPV1 desensitization. In summary, our results show that the TRPV1-ARD is an important mediator of TRPV1 desensitization, whereas TRPV1-CT has higher affinity for CaM and is likely involved in separate regulatory mechanisms. Distinct properties of Ca2+-calmodulin binding to N- and C-terminal regulatory regions of the TRPV1 channel.,Lau SY, Procko E, Gaudet R J Gen Physiol. 2012 Nov;140(5):541-55. doi: 10.1085/jgp.201210810. PMID:23109716[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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Categories: Buffalo rat | Human | Large Structures | Gaudet, R | Lau, S Y | 1-10 motif | Calcium binding protein | Calcium channel | Calcium-binding protein | Calcium-calmodulin | Calmodulin | Calmodulin complex | Calmodulin-binding | Ef hand | Ion channel | Thermosensor | Trp channel | Trpv1 | Trpv1 c-terminus
