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.External 2231691f894ba696de1310221b0a0dbbb31a7251e75115c265587c3d9d5f507c

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."]
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: 11248050External 2231691f894ba696de1310221b0a0dbbb31a7251e75115c265587c3d9d5f507c
Screening Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
  Experimental screening Non-experimental screening Reference
TRP channel construct Interactor source
TRP channel Interactor Method Species Region Species Organ/tissue Sample type
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Inference Prediction 11248050
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
Validation: In vitro validation Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
  Assay with recombinant proteins Reference
TRP channel construct Interactor construct
TRP channel Interactor Method Species Region Expression system Species Region Expression system
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Fusion protein-pull down assay Human 742-795 E. coli Rat Full-length In vitro translation 11248050
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
Characterization Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
  Binding region mapping Stoichiometry Affinity (Kd) Reference
TRP channel Interactor
TRP channel Interactor Method Species Region Species Region
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Fluorescence probe labeling Human 764-793 Bovine Not determined 100 nM 11248050
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 IP3R3 Fusion protein-pull down assay Human 761-795 Human 669-698 11248050
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
Functional consequence Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
TRP channel Interactor Method Post-translational modification Subcellular trafficking Activity Reference
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Calmodulin Patch clamp Inhibition 11248050
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 IP3R3 Patch clamp Activation 11248050
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
TRP / Interactor

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