The protein stromal interaction molecule 1 (STIM1) plays a pivotal role in mediating store-operated calcium entry (SOCE) into cells, which is essential for adaptive immunity. It acts as a calcium sensor in the endoplasmic reticulum (ER) and extends into the cytosol, where it changes from an inactive (tight) to an active (extended) oligomeric form upon calcium store depletion. NMR studies of this protein are challenging due to its membrane-spanning and aggregation properties. Therefore follow the divide-and-conquer approach, focusing on individual domains first is in order. The cytosolic part is predicted to have a large content of coiled-coil (CC) structure. We report the 1H, 13C, 15N chemical shift assignments of the CC3 domain. This domain is crucial for the stabilisation of the tight quiescent form of STIM1 as well as for activating the ORAI calcium channel by direct contact, in the extended active form.

• Keywords
• CRAC, Calcium channel, Coiled-coil structure, Store-operated calcium entry,
• MeSH
• Humans MeSH
• Neoplasm Proteins * chemistry   metabolism   MeSH
• Nuclear Magnetic Resonance, Biomolecular * MeSH
• Stromal Interaction Molecule 1 * chemistry   metabolism   MeSH
• Protein Domains * MeSH
• Amino Acid Sequence MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Neoplasm Proteins * MeSH
• Stromal Interaction Molecule 1 * MeSH
• STIM1 protein, human MeSH Browser

The calcium release activated calcium channel is activated by the endoplasmic reticulum-resident calcium sensor protein STIM1. On activation, STIM1 C terminus changes from an inactive, tight to an active, extended conformation. A coiled-coil clamp involving the CC1 and CC3 domains is essential in controlling STIM1 activation, with CC1 as the key entity. The nuclear magnetic resonance-derived solution structure of the CC1 domain represents a three-helix bundle stabilized by interhelical contacts, which are absent in the Stormorken disease-related STIM1 R304W mutant. Two interhelical sites between the CC1α1 and CC1α2 helices are key in controlling STIM1 activation, affecting the balance between tight and extended conformations. Nuclear magnetic resonance-directed mutations within these interhelical interactions restore the physiological, store-dependent activation behavior of the gain-of-function STIM1 R304W mutant. This study reveals the functional impact of interhelical interactions within the CC1 domain for modifying the CC1-CC3 clamp strength to control the activation of STIM1.

• MeSH
• Erythrocytes, Abnormal MeSH
• Dyslexia genetics   MeSH
• HEK293 Cells MeSH
• Ichthyosis genetics   MeSH
• Calcium Release Activated Calcium Channels metabolism   MeSH
• Cloning, Molecular MeSH
• Nucleic Acid Conformation MeSH
• Humans MeSH
• Magnetic Resonance Spectroscopy MeSH
• Patch-Clamp Techniques MeSH
• Migraine Disorders genetics   MeSH
• Miosis genetics   MeSH
• Models, Molecular MeSH
• Mutation genetics   MeSH
• Neoplasm Proteins genetics   MeSH
• ORAI1 Protein genetics   MeSH
• Stromal Interaction Molecule 1 genetics   MeSH
• Spleen abnormalities   MeSH
• Muscle Fatigue genetics   MeSH
• Blood Platelet Disorders genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Calcium Release Activated Calcium Channels MeSH
• Neoplasm Proteins MeSH
• ORAI1 protein, human MeSH Browser
• ORAI1 Protein MeSH
• Stromal Interaction Molecule 1 MeSH
• STIM1 protein, human MeSH Browser