Proc Natl Acad Sci U S A. 2007 Mar 13;104(11):4682-7. Epub 2007 Mar 7.

Orai proteins interact with TRPC channels and confer responsiveness to store depletion.External 2231691f894ba696de1310221b0a0dbbb31a7251e75115c265587c3d9d5f507c

Liao, Y., Erxleben, C., Yildirim, E., Abramowitz, J., Armstrong, D. L., Birnbaumer, L.,
["Signal Transduction and Neurobiology Laboratories, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA."]
The TRPC (C-type transient receptor potential) class of ion channels has been hypothesized to participate in store-operated Ca(2+) entry (SOCE). Recently, however, STIM1 and Orai1 proteins have been proposed to form SOCE channels. Whether TRPCs participate in SOCE that is dependent on or regulated by Orai has not been explored. Here we show that Orai1 physically interacts with the N and C termini of TRPC3 and TRPC6, and that in cells overexpressing either TRPC3 or TRPC6 in a store-depletion insensitive manner, these TRPCs become sensitive to store depletion upon expression of an exogenous Orai. Thus, Orai-1, -2, and -3 enhanced thapsigargin-induced calcium entry by 50-150% in cells stably overexpressing either TRPC3 or TRPC6. Orai1 expression had no significant effect on endogenous, thapsigargin-induced calcium entry in wild-type cells (HEK-293, COS1), in HEK cells expressing a thapsigargin-sensitive variant of TRPC3 (TRPC3a), or in HEK cells overexpressing another membrane protein, V1aR. Single-channel cation currents present in membrane patches of TRPC3-overexpressing cells were suppressed by expression of Orai1. We propose that Orai proteins by interacting with TRPCs act as regulatory subunits that confer STIM1-mediated store depletion sensitivity to these channels.
PMID: 17360584External 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 Orai1 Inference Prediction 17360584
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai2 Inference Prediction 17360584
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai3 Inference Prediction 17360584
TRPC6 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai1 Inference Prediction 17360584
(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 Orai1 Fusion protein-pull down assay Human 1-340 In vitro translation Human Full-length E. coli 17360584
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai1 Fusion protein-pull down assay Human 676-848 In vitro translation Human Full-length E. coli 17360584
TRPC6 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai1 Fusion protein-pull down assay Mouse 1-396 In vitro translation Human Full-length E. coli 17360584
TRPC6 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai1 Fusion protein-pull down assay Mouse 732-930 In vitro translation Human Full-length E. coli 17360584
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
Validation: In vivo validation Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
  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
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai1 Co-immunoprecipitation COS-7 Human Full-length Human Full-length 17360584
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai2 Co-immunoprecipitation COS-7 Human Full-length Human Full-length 17360584
TRPC3 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai3 Co-immunoprecipitation COS-7 Human Full-length Human Full-length 17360584
TRPC6 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Orai1 Co-immunoprecipitation HEK293 Mouse Full-length Human Full-length 17360584
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
TRP / Interactor

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