Novartis Found Symp. 2004;258:44-58; discussion 58-62, 98-102, 263-6.
TRPC channel interactions with calmodulin and IP3 receptors.
Zhu, M. X., Tang, J.,
["Center for Molecular Neurobiology and Department of Neuroscience, The Ohio State University, 168 Rightmire Hall, 1060 Carmack Road, Columbus, Ohio 43210, USA."]
["Center for Molecular Neurobiology and Department of Neuroscience, The Ohio State University, 168 Rightmire Hall, 1060 Carmack Road, Columbus, Ohio 43210, USA."]
Consistent with the conformational coupling mechanism, which suggests that store-operated channels are activated via physical interactions with intracellular calcium release channels, previous studies have demonstrated a functional coupling and a physical interaction between the transient receptor potential canonical type 3 (TRPC3) and inositol 1,4,5-trisphosphate receptor (IP3R). The IP3R-TRPC binding domains were determined using in vitro binding assays. This work aimed to study the effect of IP3R-TRPC interaction on TRPC function. Pull-down experiments were used to study the binding of TRPC to IP3R and to calmodulin. Patch clamp recordings in whole-cell and inside-out configurations were used to examine the effect of a TRPC-binding IP3R fragment, Ca2+ and calmodulin on TRPC activity. We found that IP3R and calmodulin compete for a common binding site at the TRPC C-terminus. TRPC channels are activated either by a peptide representing the TRPC-binding domain of IP3R or by inactivation of calmodulin from the excised membrane patches. TRPC3 activity is inhibited by Ca2+ and calmodulin. Therefore, we have identified a critical IP3R-TRPC interaction that is involved in the activation of TRPC-formed channels. We propose that IP3Rs activate TRPC channels by displacing inhibitory calmodulin from a common calmodulin-IP3R binding site located at the C-terminus of TRPC.
PMID: 15104175
 Screening
Validation: In vitro validation
Validation: In vivo validation
Characterization
Functional consequence
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Characterization
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| Binding region mapping | Stoichiometry | Affinity (Kd) | Reference | |||||||
| TRP channel | Interactor | |||||||||
| TRP channel | Interactor | Method | Species | Region | Species | Region | ||||
| TRPC4 |
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Calmodulin | Fusion protein-pull down assay | Mouse | 695-724 | Not specified | Not determined | 15104175 | ||
| TRPC4 |
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IP3R3 | Fusion protein-pull down assay | Mouse | 695-724 | Human | 669-698 | 15104175 | ||
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