title: Translocation between PI(4,5)P2-poor and PI(4,5)P2-rich microdomains during store depletion determines STIM1 conformation and Orai1 gating.
abstract: The Orai1-STIM1 current undergoes slow Ca(2+)-dependent inactivation (SCDI) mediated by the binding of SARAF to STIM1. Here we report the use of SCDI by SARAF as a probe of the conformation and microdomain localization of the Orai1-STIM1 complex. We find that the interaction of STIM1 with Orai1 carboxyl terminus (C terminus) and the STIM1 K-domain are required for the interaction of SARAF with STIM1 and SCDI. STIM1-Orai1 must be in a PM/ER microdomain tethered by E-Syt1, stabilized by septin4 and enriched in PI(4,5)P2 for STIM1-SARAF interaction. Targeting STIM1 to PI(4,5)P2-rich and -poor microdomains reveals that SARAF-dependent SCDI is observed only when STIM1-Orai1 are within the PI(4,5)P2-rich microdomain. Notably, store depletion results in transient localization of STIM1-Orai1 in the PI(4,5)P2-poor microdomain, which then translocates to the PI(4,5)P2-rich domain. These findings reveal the role of PM/ER tethers in the regulation of Orai1 function and a mode of regulation by PI(4,5)P2 involving translocation between PI(4,5)P2 microdomains.
authors.affiliation: 1] Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland 20892, USA [2] First Department of Medicine, University of Szeged, H-6725 Szeged, Hungary.
authors.forename: Jozsef
authors.initials: J
authors.lastname: Maléth
authors.affiliation: 1] Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland 20892, USA [2] Department of Physiology, College of Medicine, Chosun University, Chosun 501-375, South Korea.
authors.forename: Seok
authors.initials: S
authors.lastname: Choi
authors.affiliation: Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland 20892, USA.
authors.forename: Shmuel
authors.initials: S
authors.lastname: Muallem
authors.affiliation: Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland 20892, USA.
authors.forename: Malini
authors.initials: M
authors.lastname: Ahuja
mesh_terms: D001665:Binding Sites; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020013:Calcium Signaling; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D052139:Intracellular Calcium-Sensing Proteins; D015640:Ion Channel Gating; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000071740:ORAI1 Protein; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry* / Q000378:metabolism; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins; D058112:Septins / Q000235:genetics / Q000378:metabolism; D000071737:Stromal Interaction Molecule 1; D050857:Synaptotagmins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D015220:Calcium Channels; C583132:ESYT1 protein, human; D052139:Intracellular Calcium-Sensing Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; D019269:Phosphatidylinositol 4,5-Diphosphate; D011994:Recombinant Proteins; C572578:SARAF protein, human; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D050857:Synaptotagmins; C492027:SEPTIN4 protein, human; D058112:Septins; D002118:Calcium