Pflugers Arch. 2005 Aug;450(5):345-54. Epub 2005 May 14.

Inhibition of TRPC5 channels by Ca2+-binding protein 1 in Xenopus oocytes.External

Kinoshita-Kawada, M., Tang, J., Xiao, R., Kaneko, S., Foskett, J. K., Zhu, M. X.,
["Department of Neuroscience and Center for Molecular Neurobiology, The Ohio State University, 168 Rightmire Hall, 1060 Carmack Road, Columbus, OH 43210, USA."]
The transient receptor potential canonical type 5 (TRPC5) channel is a member of the channels that has been implicated in neurite extension and growth cone morphology of hippocampal neurons. Although homomeric TRPC5 channels are activated following stimulation of G(q/11)-coupled receptors, the exact mechanism for this activation remains unresolved. Using two-electrode voltage clamp recordings, we show that the activity of TRPC5 channels expressed in Xenopus oocytes is dependent on the presence of Ca2+ at the extracellular as well as the cytoplasmic side of the plasma membrane. TRPC5 was activated by the stimulation of coexpressed M5 muscarinic receptors or by ionomycin. The TRPC5 activity was detectable with the presence of submillimolar levels of extracellular Ca2+, but it was eliminated by the injection of 5 mM 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid into the oocytes. Lanthanum could substitute for extracellular Ca2+ to support TRPC5 activity. Coexpression of Ca2+-binding protein 1 (CaBP1), but not calmodulin (CaM), inhibited the TRPC5 activity, without affecting the cell surface expression of TRPC5 proteins. Using in vitro binding assays, we demonstrated direction interactions between CaBP1 and TRPC5. The CaBP1-binding sites at the C terminus of TRPC5 are closely localized, but not identical, to CaM-binding sites. We conclude that TRPC5 is a Ca2+-regulated channel, and its activity is negatively controlled by CaBP1.
PMID: 15895247External
Arrow2 Screening Arrow2 Validation: In vitro validation Arrow2 Validation: In vivo validation Arrow2 Characterization Arrow2 Functional consequence Arrow2 top
Screening Toggle
  Experimental screening Non-experimental screening Reference
TRP channel construct Interactor source
TRP channel Interactor Method Species Region Species Organ/tissue Sample type
TRPC5 Link CaBP1 Inference Prediction 15895247
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Validation: In vitro validation Toggle
  Assay with recombinant proteins Reference
TRP channel construct Interactor construct
TRP channel Interactor Method Species Region Expression system Species Region Expression system
TRPC5 Link CaBP1 Fusion protein-pull down assay Mouse Full-length E. coli Human Full-length E. coli 15895247
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Characterization Toggle
  Binding region mapping Stoichiometry Affinity (Kd) Reference
TRP channel Interactor
TRP channel Interactor Method Species Region Species Region
TRPC5 Link CaBP1 Fusion protein-pull down assay Mouse 1-331 Human Not determined 15895247
TRPC5 Link CaBP1 Fusion protein-pull down assay Mouse 721-817 Human Not determined 15895247
TRPC5 Link CaBP1 Fusion protein-pull down assay Mouse 791-866 Human Not determined 15895247
(Link: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
Arrow2 Screening Arrow2 Validation: In vitro validation Arrow2 Validation: In vivo validation Arrow2 Characterization Arrow2 Functional consequence Arrow2 top
Functional consequence Toggle
TRP channel Interactor Method Post-translational modification Subcellular trafficking Activity Reference
TRPC5 Link CaBP1 Patch clamp Inhibition 15895247
(Link: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
TRP / Interactor

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