EMBO J. 2006 Jul 12;25(13):2978-88. Epub 2006 Jun 8.

Calbindin-D28K dynamically controls TRPV5-mediated Ca2+ transport.External

Lambers, T. T., Mahieu, F., Oancea, E., Hoofd, L., de Lange, F., Mensenkamp, A. R., Voets, T., Nilius, B., Clapham, D. E., Hoenderop, J. G., Bindels, R. J.,
["Department of Physiology, Radboud University Nijmegen Medical Centre, The Netherlands."]
In Ca(2+)-transporting epithelia, calbindin-D(28K) (CaBP(28K)) facilitates Ca(2+) diffusion from the luminal Ca(2+) entry side of the cell to the basolateral side, where Ca(2+) is extruded into the extracellular compartment. Simultaneously, CaBP(28K) provides protection against toxic high Ca(2+) levels by buffering the cytosolic Ca(2+) concentration ([Ca(2+)](i)) during high Ca(2+) influx. CaBP(28K) consistently colocalizes with the epithelial Ca(2+) channel TRPV5, which constitutes the apical entry step in renal Ca(2+)-transporting epithelial cells. Here, we demonstrate using protein-binding analysis, subcellular fractionation and evanescent-field microscopy that CaBP(28K) translocates towards the plasma membrane and directly associates with TRPV5 at a low [Ca(2+)](i). (45)Ca(2+) uptake measurements, electrophysiological recordings and transcellular Ca(2+) transport assays of lentivirus-infected primary rabbit connecting tubule/distal convolute tubule cells revealed that associated CaBP(28K) tightly buffers the flux of Ca(2+) entering the cell via TRPV5, facilitating high Ca(2+) transport rates by preventing channel inactivation. In summary, CaBP(28K) acts in Ca(2+)-transporting epithelia as a dynamic Ca(2+) buffer, regulating [Ca(2+)] in close vicinity to the TRPV5 pore by direct association with the channel.
PMID: 16763551External
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Screening Toggle
  Experimental screening Non-experimental screening Reference
TRP channel construct Interactor source
TRP channel Interactor Method Species Region Species Organ/tissue Sample type
TRPV5 Link Calbindin-D28K Inference Prediction 16763551
TRPV6 Link Calbindin-D28K Inference Prediction 16763551
(Link: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
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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
TRPV5 Link Calbindin-D28K Fusion protein-pull down assay Mouse N-terminus E. coli Not specified Full-length In vitro translation 16763551
TRPV5 Link Calbindin-D28K Fusion protein-pull down assay Mouse C-terminus E. coli Not specified Full-length In vitro translation 16763551
TRPV6 Link Calbindin-D28K Fusion protein-pull down assay Mouse N-terminus E. coli Not specified Full-length In vitro translation 16763551
TRPV6 Link Calbindin-D28K Fusion protein-pull down assay Mouse C-terminus E. coli Not specified Full-length In vitro translation 16763551
(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
Validation: In vivo validation Toggle
  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
TRPV5 Link Calbindin-D28K Co-immunofluorescence staining Mouse kidney section 16763551
TRPV5 Link Calbindin-D28K Co-immunoprecipitation HEK293 Mouse Full-length Not specified Full-length 16763551
(Link: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
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Functional consequence Toggle
TRP channel Interactor Method Post-translational modification Subcellular trafficking Activity Reference
TRPV5 Link Calbindin-D28K Patch clamp Activation 16763551
(Link: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
TRP / Interactor

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