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Distinct gating mechanism of SOC channel involving STIM-Orai coupling and an intramolecular interaction of Orai in Caenorhabditis elegans

  • Kim, Kyu Min
  • Wijerathne, Tharaka
  • Hur, Jin-Hoe
  • Kang, Uk Jung
  • Kim, Ihn Hyeong
  • Kweon, Yeong Cheon
  • Lee, Ah Reum
  • Jeong, Su Ji
  • Lee, Sang Kwon
  • Lee, Yoon Young
  • Sim, Bo-Woong
  • Lee, Jong-Hee
  • Baig, Chunggi
  • Kim, Sun-Uk
  • Chang, Kyu-Tae
  • Lee, Kyu Pil
  • Park, Chan Young
Publication Date
Jun 09, 2018
[email protected]
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Store-operated calcium entry (SOCE), an important mechanism of Ca2+ signaling in a wide range of cell types, is mediated by stromal interaction molecule (STIM), which senses the depletion of endoplasmic reticulum Ca2+ stores and binds and activates Orai channels in the plasma membrane. This inside-out mechanism of Ca2+ signaling raises an interesting question about the evolution of SOCE: How did these two proteins existing in different cellular compartments evolve to interact with each other? We investigated the gating mechanism of Caenorhabditis elegans Orai channels. Our analysis revealed a mechanism of Orai gating by STIM binding to the intracellular 2-3 loop of Orai in C. elegans that is radically different from Orai gating by STIM binding to the N and C termini of Orai in mammals. In addition, we found that the conserved hydrophobic amino acids in the 2-3 loop of Orai1 are important for the oligomerization and gating of channels and are regulated via an intramolecular interaction mechanism mediated by the N and C termini of Orai1. This study identifies a previously unknown SOCE mechanism in C. elegans and suggests that, while the STIM-Orai interaction is conserved between invertebrates and mammals, the gating mechanism for Orai channels differs considerably.

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