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EMBO J. 2015 Sep 2;34(17):2291-305. doi: 10.15252/embj.201591565. Epub 2015 Jul 22.

Triggered Ca2+ influx is required for extended synaptotagmin 1-induced ER-plasma membrane tethering.

Author information

1
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, USA olof.idevall@mcb.uu.se pietro.decamilli@yale.edu.
2
Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, USA.
3
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
4
Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, USA olof.idevall@mcb.uu.se pietro.decamilli@yale.edu.

Abstract

The extended synaptotagmins (E-Syts) are ER proteins that act as Ca(2+)-regulated tethers between the ER and the plasma membrane (PM) and have a putative role in lipid transport between the two membranes. Ca(2+) regulation of their tethering function, as well as the interplay of their different domains in such function, remains poorly understood. By exposing semi-intact cells to buffers of variable Ca(2+) concentrations, we found that binding of E-Syt1 to the PI(4,5)P2-rich PM critically requires its C2C and C2E domains and that the EC50 of such binding is in the low micromolar Ca(2+) range. Accordingly, E-Syt1 accumulation at ER-PM contact sites occurred only upon experimental manipulations known to achieve these levels of Ca(2+) via its influx from the extracellular medium, such as store-operated Ca(2+) entry in fibroblasts and membrane depolarization in β-cells. We also show that in spite of their very different physiological functions, membrane tethering by E-Syt1 (ER to PM) and by synaptotagmin (secretory vesicles to PM) undergo a similar regulation by plasma membrane lipids and cytosolic Ca(2+).

KEYWORDS:

Orai1; PLC; STIM1; membrane contact sites; tricalbin

PMID:
26202220
PMCID:
PMC4585464
DOI:
10.15252/embj.201591565
[Indexed for MEDLINE]
Free PMC Article

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