Pflugers Arch. 2008 Oct;457(1):91-101. doi: 10.1007/s00424-008-0494-5. Epub 2008 Apr 8.
Identification of Nipsnap1 as a novel auxiliary protein inhibiting TRPV6 activity.
Schoeber, J. P., Topala, C. N., Lee, K. P., Lambers, T. T., Ricard, G., van der Kemp, A. W., Huynen, M. A., Hoenderop, J. G., Bindels, R. J.,
["Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands."]
["Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands."]
The transient receptor potential vanilloid channels 5 and 6 (TRPV5/6) are the most Ca(2+)-selective channels within the TRP superfamily of ion channels. These epithelial Ca(2+) channels are regulated at different intra- and extracellular sites by the feedback response of Ca(2+) itself, calciotropic hormones, and by TRPV5/6-associated proteins. In the present study, bioinformatics was used to search for novel TRPV5/6-associated genes. By including pull-down assays and functional analysis, Nipsnap1-a hitherto functionally uncharacterized globular protein-was identified as a novel factor involved in the regulation of TRPV6. Electrophysiological recordings revealed that Nipsnap1 abolishes TRPV6 currents. Subsequent biotinylation assays showed that TRPV6 plasma membrane expression did not change in the presence of Nipsnap1, suggesting that TRPV6 inhibition by Nipsnap1 is independently regulated from reduced cell surface channel expression. In addition, semi-quantitative reverse transcriptase PCR and immunohistochemical labeling of Nipsnap1 indicated that Nipsnap1 is expressed in mouse intestinal tissues-where TRPV6 is predominantly expressed-but that it does not co-localize with TRPV5 in the kidney. In conclusion, this study presents the first physiological function of Nipsnap1 as an associated protein inhibiting TRPV6 activity that possibly exerts its effect directly at the plasma membrane.
PMID: 18392847

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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 | |||
TRPV5 |
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Nipsnap1 | Inference | Prediction | 18392847 | |||||
TRPV6 |
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Nipsnap1 | Inference | Prediction | 18392847 |
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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 | ||
TRPV6 |
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Nipsnap1 | Fusion protein-pull down assay | Mouse | 577-607 | E. coli | Not specified | Full-length | E. coli | 18392847 |
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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 vivo validation
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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 |
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Nipsnap1 | Co-immunoprecipitation | HEK293 | Rabbit | Full-length | Not specified | Full-length | 18392847 | |
TRPV6 |
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Nipsnap1 | Co-immunoprecipitation | HEK293 | Mouse | Full-length | Not specified | Full-length | 18392847 |
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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 | ||||
TRPV6 |
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Nipsnap1 | Fusion protein-pull down assay | Mouse | 83-118 | Not specified | Not determined | 18392847 |
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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 | ||||||
TRPV6 |
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Nipsnap1 | Patch clamp | Inhibition | 18392847 |
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
