Abstract
The mechanism involved in [Ca(2+)](i)-dependent feedback inhibition of store-operated Ca(2+) entry (SOCE) is not yet known. Expression of Ca(2+)-insensitive calmodulin (Mut-CaM) but not wild-type CaM increased SOCE and decreased its Ca(2+)-dependent inactivation. Expression of TrpC1 lacking C terminus aa 664-793 (TrpC1DeltaC) also attenuated Ca(2+)-dependent inactivation of SOCE. CaM interacted with endogenous and expressed TrpC1 and with GST-TrpC1 C terminus but not with TrpC1DeltaC. Two CaM binding domains, aa 715-749 and aa 758-793, were identified. Expression of TrpC1Delta758-793 but not TrpC1Delta715-749 mimicked the effects of TrpC1DeltaC and Mut-CaM on SOCE. These data demonstrate that CaM mediates Ca(2+)-dependent feedback inhibition of SOCE via binding to a domain in the C terminus of TrpC1. These findings reveal an integral role for TrpC1 in the regulation of SOCE.
MeSH terms
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Amino Acid Substitution
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Binding Sites
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Calcium Channels / chemistry
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Calcium Channels / metabolism*
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Calcium Channels / physiology
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Calcium Signaling / physiology*
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Calmodulin / chemistry
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Calmodulin / genetics
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Calmodulin / physiology*
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Cell Compartmentation
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Cell Line / drug effects
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Cell Line / metabolism
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DNA, Complementary / genetics
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Epithelial Cells / drug effects
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Epithelial Cells / metabolism
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Feedback
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Humans
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Ion Channel Gating / physiology
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Ion Transport / physiology
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Mutagenesis, Site-Directed
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Patch-Clamp Techniques
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Peptide Fragments / metabolism
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Protein Binding
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Protein Interaction Mapping
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Protein Structure, Tertiary
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / metabolism
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Sequence Deletion
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Submandibular Gland / cytology
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TRPC Cation Channels
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Transfection
Substances
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Calcium Channels
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Calmodulin
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DNA, Complementary
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Peptide Fragments
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Recombinant Fusion Proteins
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TRPC Cation Channels
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transient receptor potential cation channel, subfamily C, member 1