Proc Natl Acad Sci U S A. 2001 Mar 13;98(6):3168-73. Epub 2001 Feb 27.
Activation of Trp3 by inositol 1,4,5-trisphosphate receptors through displacement of inhibitory calmodulin from a common binding domain.
Zhang, Z., Tang, J., Tikunova, S., Johnson, J. D., Chen, Z., Qin, N., Dietrich, A., Stefani, E., Birnbaumer, L., Zhu, M. X.,
["Neurobiotechnology Center and Departments of Neuroscience and Molecular and Cellular Biochemistry, Ohio State University, Columbus, OH 43210, USA."]
["Neurobiotechnology Center and Departments of Neuroscience and Molecular and Cellular Biochemistry, Ohio State University, Columbus, OH 43210, USA."]
Mammalian homologues of Drosophila Trp form plasma membrane channels that mediate Ca(2+) influx in response to activation of phospholipase C and internal Ca(2+) store depletion. Previous studies showed that human Trp3 is activated by inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)Rs) and identified interacting domains, one on Trp and two on IP(3)R. We now find that Trp3 binds Ca(2+)-calmodulin (Ca(2+)/CaM) at a site that overlaps with the IP(3)R binding domain. Using patch-clamp recordings from inside-out patches, we further show that Trp3 has a high intrinsic activity that is suppressed by Ca(2+)/CaM under resting conditions, and that Trp3 is activated by the following: a Trp-binding peptide from IP(3)R that displaces CaM from Trp3, a myosin light chain kinase Ca(2+)/CaM binding peptide that prevents CaM from binding to Trp3, and calmidazolium, an inactivator of Ca(2+)/CaM. We conclude that inhibition of the inhibitory action of CaM is a key step of Trp3 channel activation by IP(3)Rs.
PMID: 11248050

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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 | |||
TRPC3 |
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Calmodulin | Inference | Prediction | 11248050 |
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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 | ||
TRPC3 |
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Calmodulin | Fusion protein-pull down assay | Human | 742-795 | E. coli | Rat | Full-length | In vitro translation | 11248050 |
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)

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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 | ||||
TRPC3 |
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Calmodulin | Fluorescence probe labeling | Human | 764-793 | Bovine | Not determined | 100 nM | 11248050 | |
TRPC3 |
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IP3R3 | Fusion protein-pull down assay | Human | 761-795 | Human | 669-698 | 11248050 |
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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 | ||||||
TRPC3 |
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Calmodulin | Patch clamp | Inhibition | 11248050 | |||||||
TRPC3 |
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IP3R3 | Patch clamp | Activation | 11248050 |
(
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
