scholarly journals Identification and characterization of two distinct calmodulin-binding sites in the Trpl ion-channel protein of Drosophila melanogaster

1996 ◽  
Vol 314 (2) ◽  
pp. 497-503 ◽  
Author(s):  
Coral G. WARR ◽  
Leonard E. KELLY
Keyword(s):  
Protein Kinase ◽  
Ion Channel ◽  
Binding Sites ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Free Form ◽  
Calmodulin Binding ◽  
Dependent Protein ◽  
Transient Receptor

Two putative light-sensitive ion channels have been isolated from Drosophila, encoded by the transient-receptor-potential (trp) and transient-receptor-potential-like (trpl) genes. The cDNA encoding the Trpl protein was initially isolated on the basis that the expressed protein binds calmodulin. Using both fusion proteins and a synthetic peptide, we now show that two calmodulin-binding sites are present in the C-terminal domain of the Trpl protein, CBS-1 and CBS-2. CBS-1 binds calmodulin in a Ca2+-dependent fashion, requiring Ca2+ concentrations above 0.3–0.5 μM for calmodulin binding. In contrast, CBS-2 binds the Ca2+-free form of calmodulin, with dissociation occurring at Ca2+ concentrations between 5 and 25 μM. Phosphorylation of a serine residue within a peptide encompassing CBS-1 by cyclic AMP-dependent protein kinase (PKA) abolishes calmodulin binding, and phosphorylation of the adjacent serine by protein kinase C appears to modulate this phosphorylation by PKA. Interpretation of these findings provides a novel model for ion-channel gating and modulation in response to changing levels of intracellular Ca2+.

scholarly journals TRPV1: Structure, Endogenous Agonists, and Mechanisms

2020 ◽  
Vol 21 (10) ◽  
pp. 3421 ◽  
Author(s):  
Miguel Benítez-Angeles ◽  
Sara Luz Morales-Lázaro ◽  
Emmanuel Juárez-González ◽  
Tamara Rosenbaum
Keyword(s):  
Ion Channel ◽  
Binding Sites ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Trpv1 Channel ◽  
Field Of Study ◽  
Transient Receptor ◽  
Shed Light ◽  
Made In

The Transient Receptor Potential Vanilloid 1 (TRPV1) channel is a polymodal protein with functions widely linked to the generation of pain. Several agonists of exogenous and endogenous nature have been described for this ion channel. Nonetheless, detailed mechanisms and description of binding sites have been resolved only for a few endogenous agonists. This review focuses on summarizing discoveries made in this particular field of study and highlighting the fact that studying the molecular details of activation of the channel by different agonists can shed light on biophysical traits that had not been previously demonstrated.

scholarly journals Expression and role of TRPC proteins in human platelets: evidence that TRPC6 forms the store-independent calcium entry channel

Blood ◽  
2002 ◽  
Vol 100 (8) ◽  
pp. 2801-2811 ◽  
Author(s):  
Sheila R. Hassock ◽  
Michael X. Zhu ◽  
Claudia Trost ◽  
Veit Flockerzi ◽  
Kalwant S. Authi
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinases ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Human Platelets ◽  
Major Pathway ◽  
Dependent Protein ◽  
Transient Receptor ◽  
And Function ◽  
Trpc Proteins

Store-operated Ca++ entry (SOCE) is thought to comprise the major pathway for Ca++ entry in platelets. Recently, a number of transient receptor potential (TRP) proteins, which have been divided into 3 groups (TRPC, TRPM, and TRPV), have been suggested as SOCE channels. We report the expression and function of TRPC proteins in human platelets. TRPC6 is found at high levels and TRPC1 at low levels. Using purified plasma (PM) and intracellular membranes (IM), TRPC6 is found in the PM, but TRPC1 is localized to the IM. Using Fura-2–loaded platelets, we report that, in line with TRPC6 expression, 1-oleoyl-2-acetyl-sn-glycerol (OAG) stimulated the entry of Ca++ and Ba2+ independently of protein kinase C. Thrombin also induced the entry of Ca++ and Ba2+, but thapsigargin, which depletes the stores, induced the entry of only Ca++. Thus, thrombin activated TRPC6 via a SOCE-independent mechanism. In phosphorylation studies, we report that neither TRPC6 nor TRPC1 was a substrate for tyrosine kinases. TRPC6 was phosphorylated by cAMP-dependent protein kinase (cAMP-PK) and associated with other cAMP-PK substrates. TRPC1 was not phosphorylated by cAMP-PK but also associated with other substrates. Activation of cAMP-PK inhibited Ca++ but not Ba2+ entry induced by thrombin and neither Ca++ nor Ba2+entry stimulated by OAG. These results suggest that TRPC6 is a SOCE-independent, nonselective cation entry channel stimulated by thrombin and OAG. TRPC6 is a substrate for cAMP-PK, although phosphorylation appears to not affect cation permeation. TRPC1 is located in IM, suggesting a role at the level of the stores.

scholarly journals Druggable Lipid Binding Sites in Pentameric Ligand-Gated Ion Channels and Transient Receptor Potential Channels

2022 ◽  
Vol 12 ◽  
Author(s):  
Wayland W. L. Cheng ◽  
Mark J. Arcario ◽  
John T. Petroff
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Binding Sites ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Lipid Binding ◽  
Transient Receptor Potential Channels ◽  
Allosteric Modulators ◽  
Potential Channels ◽  
Transient Receptor

Lipids modulate the function of many ion channels, possibly through direct lipid-protein interactions. The recent outpouring of ion channel structures by cryo-EM has revealed many lipid binding sites. Whether these sites mediate lipid modulation of ion channel function is not firmly established in most cases. However, it is intriguing that many of these lipid binding sites are also known sites for other allosteric modulators or drugs, supporting the notion that lipids act as endogenous allosteric modulators through these sites. Here, we review such lipid-drug binding sites, focusing on pentameric ligand-gated ion channels and transient receptor potential channels. Notable examples include sites for phospholipids and sterols that are shared by anesthetics and vanilloids. We discuss some implications of lipid binding at these sites including the possibility that lipids can alter drug potency or that understanding protein-lipid interactions can guide drug design. Structures are only the first step toward understanding the mechanism of lipid modulation at these sites. Looking forward, we identify knowledge gaps in the field and approaches to address them. These include defining the effects of lipids on channel function in reconstituted systems using asymmetric membranes and measuring lipid binding affinities at specific sites using native mass spectrometry, fluorescence binding assays, and computational approaches.

Characterization of the function of transient receptor potential melastatin 2 in mouse pancreas

Pancreatology ◽  
2019 ◽  
Vol 19 ◽  
pp. S94
Author(s):  
Júlia Fanczal ◽  
Petra Pallagi ◽  
Marietta Görög ◽  
Csaba Péter Bíró ◽  
Tamara Madácsy ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Mouse Pancreas ◽  
Transient Receptor Potential Melastatin ◽  
Transient Receptor
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