J Biol Chem. 2003 Dec 26;278(52):52763-72. Epub 2003 Oct 6.
Inhibitor of myogenic family, a novel suppressor of store-operated currents through an interaction with TRPC1.
Ma, R., Rundle, D., Jacks, J., Koch, M., Downs, T., Tsiokas, L.,
["Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA."]
["Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA."]
Depletion of intracellular Ca2+ stores leads to the activation of Ca2+ inflow through store-operated Ca2+ channels. Although the identity of these channels is unknown, there is considerable evidence that the transient receptor potential channel 1 (TRPC1) participates in the formation of these channels. We show that TRPC1 physically interacts with the a-isoform of the inhibitor of the myogenic family (I-mfa), a known inhibitor of basic helix-loop-helix transcription factors, in vitro and in vivo. The interaction is mediated by the C-terminal cytoplasmic tail of TRPC1 and the C-terminal cysteine-rich domain of I-mfa. Using the whole cell configuration of the patch clamp technique, we show that ectopic expression of I-mfa in CHO-K1 cells reduces native store-activated Ca2+ currents, whereas knock-down of endogenous I-mfa in A431 cells by RNA interference enhances these currents. Pipette perfusion of purified recombinant I-mfa rescues the effect of I-mfa knock-down on store-operated conductance. Finally, cell dialysis with a monoclonal antibody specific to TRPC1 results in the suppression of store-activated conductance in cells lacking I-mfa, but not in I-mfa expressing cells. We propose that I-mfa functions as a molecular switch to suppress the store dependence of TRPC1.
PMID: 14530267

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Screening
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Experimental screening | Non-experimental screening | Reference | ||||||||
TRP channel construct | Interactor source | |||||||||
TRP channel | Interactor | Method | Species | Region | Species | Organ/tissue | Sample type | |||
TRPC1 |
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I-MFA | Yeast two-hybrid | Human | 639-750 | Mouse | Embryonic | cDNA library | 14530267 | |
TRPC1 |
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I-MFA | Yeast two-hybrid | Human | 639-750 | Human | Fetal kidney | cDNA library | 14530267 |
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

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Validation: In vitro validation
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Assay with recombinant proteins | Reference | |||||||||
TRP channel construct | Interactor construct | |||||||||
TRP channel | Interactor | Method | Species | Region | Expression system | Species | Region | Expression system | ||
TRPC1 |
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I-MFA | Fusion protein-pull down assay | Human | 639-750 | E. coli | Human | Full-length | E. coli | 14530267 |
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

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Validation: In vivo validation
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Assay with endogenous proteins | Assay with overexpressed proteins | Reference | ||||||||
Cell or tissue | Cell or tissue | TRP channel construct | Interactor construct | |||||||
TRP channel | Interactor | Method | Species | Region | Species | Region | ||||
TRPC1 |
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I-MFA | Co-immunoprecipitation | HEK293T | Human | Full-length | Human | Full-length | 14530267 | |
TRPC1 |
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I-MFA | Co-immunoprecipitation | Rat liver tissue | 14530267 | |||||
TRPC1 |
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I-MFA | Co-immunoprecipitation | NALM-6 | 14530267 | |||||
TRPC1 |
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I-MFA | Co-immunoprecipitation | Rat kidney tissue | 14530267 | |||||
TRPC1 |
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TRPP1 | Co-immunoprecipitation | HEK293T | Human | Full-length | Not specified | Not specified | 14530267 | |
TRPP1 |
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TRPC1 | Co-immunoprecipitation | HEK293T | Not specified | Not specified | Human | Full-length | 14530267 |
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

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Functional consequence
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TRP channel | Interactor | Method | Post-translational modification | Subcellular trafficking | Activity | Reference | ||||||
TRPC1 |
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I-MFA | Patch clamp | Inhibition | 14530267 |
(
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
