The stromal interaction molecule 1 (STIM1) has two important functions, Ca2+ sensing within the endoplasmic reticulum and activation of the store-operated Ca2+ channel Orai1, enabling plasma-membrane Ca2+ influx. We combined molecular dynamics (MD) simulations with live-cell recordings and determined the sequential Ca2+-dependent conformations of the luminal STIM1 domain upon activation. Furthermore, we identified the residues within the canonical and noncanonical EF-hand domains that can bind to multiple Ca2+ ions. In MD simulations, a single Ca2+ ion was sufficient to stabilize the luminal STIM1 complex. Ca2+ store depletion destabilized the two EF hands, triggering disassembly of the hydrophobic cleft that they form together with the stable SAM domain. Point mutations associated with tubular aggregate myopathy or cancer that targeted the canonical EF hand, and the hydrophobic cleft yielded constitutively clustered STIM1, which was associated with activation of Ca2+ entry through Orai1 channels. On the basis of our results, we present a model of STIM1 Ca2+ binding and refine the currently known initial steps of STIM1 activation on a molecular level.
- MeSH
- algoritmy MeSH
- buněčná membrána metabolismus MeSH
- endoplazmatické retikulum metabolismus MeSH
- HEK293 buňky MeSH
- hydrofobní a hydrofilní interakce MeSH
- konfokální mikroskopie MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- motivy EF-ruky MeSH
- mutace MeSH
- nádorové buněčné linie MeSH
- nádorové proteiny chemie genetika metabolismus MeSH
- protein ORAI1 chemie metabolismus MeSH
- protein STIM1 chemie genetika metabolismus MeSH
- proteinové domény * MeSH
- rozbalení proteinů * MeSH
- simulace molekulární dynamiky * MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
