J Biol Chem. 2005 Feb 25;280(8):6423-33. Epub 2004 Dec 7.
Regulation of the Ca2+ sensitivity of the nonselective cation channel TRPM4.
Nilius, B., Prenen, J., Tang, J., Wang, C., Owsianik, G., Janssens, A., Voets, T., Zhu, M. X.,
["Department of Physiology, Campus Gasthuisberg, KU Leuven, B-3000 Leuven, Belgium. bernd.nilius@med.kuleuven.ac.be"]
["Department of Physiology, Campus Gasthuisberg, KU Leuven, B-3000 Leuven, Belgium. bernd.nilius@med.kuleuven.ac.be"]
TRPM4, a Ca(2+)-activated cation channel of the transient receptor potential superfamily, undergoes a fast desensitization to Ca(2+). The mechanisms underlying the alterations in Ca(2+) sensitivity are unknown. Here we show that cytoplasmic ATP reversed Ca(2+) sensitivity after desensitization, whereas mutations to putative ATP binding sites resulted in faster and more complete desensitization. Phorbol ester-induced activation of protein kinase C (PKC) increased the Ca(2+) sensitivity of wild-type TRPM4 but not of two mutants mutated at putative PKC phosphorylation sites. Overexpression of a calmodulin mutant unable to bind Ca(2+) dramatically reduced TRPM4 activation. We identified five Ca(2+)-calmodulin binding sites in TRPM4 and showed that deletion of any of the three C-terminal sites strongly impaired current activation by reducing Ca(2+) sensitivity and shifting the voltage dependence of activation to very positive potentials. Thus, the Ca(2+) sensitivity of TRPM4 is regulated by ATP, PKC-dependent phosphorylation, and calmodulin binding at the C terminus.
PMID: 15590641
 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 | |||
| TRPM4 |
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Calmodulin | Inference | Prediction | 15590641 | |||||
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
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click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
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Screening
Validation: In vitro validation
Validation: In vivo validation
Characterization
Functional consequence
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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 | ||||
| TRPM4 |
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Calmodulin | Fusion protein-pull down assay | Human | 5-25 | Not specified | Not determined | 15590641 | ||
| TRPM4 |
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Calmodulin | Fusion protein-pull down assay | Human | 186-212 | Not specified | Not determined | 15590641 | ||
| TRPM4 |
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Calmodulin | Fusion protein-pull down assay | Human | 1076-1098 | Not specified | Not determined | 15590641 | ||
| TRPM4 |
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Calmodulin | Fusion protein-pull down assay | Human | 1146-1167 | Not specified | Not determined | 15590641 | ||
| TRPM4 |
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Calmodulin | Fusion protein-pull down assay | Human | 1095-1151 | Not specified | Not determined | 15590641 | ||
(:
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
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top
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| Functional consequence
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| TRP channel | Interactor | Method | Post-translational modification | Subcellular trafficking | Activity | Reference | ||||||
| TRPM4 |
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Calmodulin | Patch clamp | Activation | 15590641 | |||||||
(:
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)