Dev Biol. 2004 Oct 15;274(2):426-35.
Enkurin is a novel calmodulin and TRPC channel binding protein in sperm.
Sutton, K. A., Jungnickel, M. K., Wang, Y., Cullen, K., Lambert, S., Florman, H. M.,
["Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA."]
["Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA."]
The TRPC cation channel family has been implicated in receptor- or phospholipase C (PLC)-mediated Ca2+ entry into animal cells. These channels are present in mammalian sperm and are assigned a role in ZP3-evoked Ca2+ influx that drives acrosome reactions. However, the mechanisms controlling channel activity and coupling Ca2+ entry through these channels to cellular responses are not well understood. A yeast two-hybrid screen was carried out to identify TRPC-interacting proteins that would be candidate regulators or effectors. We identified a novel protein, enkurin, that is expressed at high levels in the testis and vomeronasal organ and at lower levels in selected other tissues. Enkurin interacts with several TRPC proteins (TRPC1, TRPC2, TRPC5, but not TRPC3) and colocalizes with these channels in sperm. Three protein-protein interaction domains were identified in enkurin: a C-terminal region is essential for channel interaction; an IQ motif binds the Ca2+ sensor, calmodulin, in a Ca2+-dependent manner; and a proline-rich N-terminal region contains predicted ligand sequences for SH3 domain proteins, including the SH3 domain of the p85 regulatory subunit of 1-phosphatidylinositol-3-kinase. We suggest that enkurin is an adaptor that functions to localize a Ca2+ sensitive signal transduction machinery in sperm to a Ca2+-permeable ion channel.
PMID: 15385169
 Screening
Validation: In vitro validation
Validation: In vivo validation
Characterization
Functional consequence
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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 | |||
| TRPC1 |
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Enkurin | Inference | Prediction | 15385169 | |||||
| TRPC2 |
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Enkurin | Yeast two-hybrid | Mouse | 34-526 | Mouse | Testis | cDNA library | 15385169 | |
| TRPC5 |
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Enkurin | Inference | Prediction | 15385169 | |||||
(:
click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
:
click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
|
Screening
Validation: In vitro validation
Validation: In vivo validation
Characterization
Functional consequence
|
top
|
| 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 | ||
| TRPC1 |
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Enkurin | Yeast two-hybrid | Human | N-terminus | Yeast | Mouse | Full-length | Yeast | 15385169 |
| TRPC1 |
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Enkurin | Fusion protein-pull down assay | Human | Full-length | HEK293 lysates | Mouse | Full-length | HEK293 lysates | 15385169 |
| TRPC5 |
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Enkurin | Yeast two-hybrid | Mouse | N-terminus | Yeast | Mouse | Full-length | Yeast | 15385169 |
| TRPC5 |
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Enkurin | Fusion protein-pull down assay | Mouse | Full-length | E. coli | Mouse | Full-length | HEK293 lysates | 15385169 |
(:
click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
:
click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)