Calmodulin regulates Ca(2+)-dependent feedback inhibition of store-operated Ca(2+) influx by interaction with a site in the C terminus of TrpC1.
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.
Singh
Brij B
BB
Secretory Physiology Section, Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
Liu
Xibao
X
Tang
Jisen
J
Zhu
Michael X
MX
Ambudkar
Indu S
IS
D019943:Amino Acid Substitution; D001665:Binding Sites; D015220:Calcium Channels / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology*; D002147:Calmodulin / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002451:Cell Compartmentation; D002460:Cell Line / Q000187:drug effects / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005246:Feedback; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology; D017136:Ion Transport / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D013363:Submandibular Gland / Q000166:cytology; D050052:TRPC Cation Channels; D014162:Transfection
D015220:Calcium Channels; D002147:Calmodulin; D018076:DNA, Complementary; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1