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- EMDB-7539: Cryo-EM structure of the human SK4/calmodulin channel complex in ... -
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Open data
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Basic information
Entry | Database: EMDB / ID: EMD-7539 | |||||||||
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Title | Cryo-EM structure of the human SK4/calmodulin channel complex in the Ca2+ bound state II | |||||||||
![]() | human SK4/calmodulin channel complex in the Ca2+ bound state II: sharpened, filtered map | |||||||||
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Function / homology | ![]() intermediate conductance calcium-activated potassium channel activity / small conductance calcium-activated potassium channel activity / saliva secretion / Ca2+ activated K+ channels / ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Similarity search - Function | |||||||||
Biological species | ![]() ![]() | |||||||||
Method | ![]() ![]() | |||||||||
![]() | Lee CH / MacKinnon R | |||||||||
Funding support | ![]()
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![]() | ![]() Title: Activation mechanism of a human SK-calmodulin channel complex elucidated by cryo-EM structures. Authors: Chia-Hsueh Lee / Roderick MacKinnon / ![]() Abstract: Small-conductance Ca-activated K (SK) channels mediate neuron excitability and are associated with synaptic transmission and plasticity. They also regulate immune responses and the size of blood ...Small-conductance Ca-activated K (SK) channels mediate neuron excitability and are associated with synaptic transmission and plasticity. They also regulate immune responses and the size of blood cells. Activation of SK channels requires calmodulin (CaM), but how CaM binds and opens SK channels has been unclear. Here we report cryo-electron microscopy (cryo-EM) structures of a human SK4-CaM channel complex in closed and activated states at 3.4- and 3.5-angstrom resolution, respectively. Four CaM molecules bind to one channel tetramer. Each lobe of CaM serves a distinct function: The C-lobe binds to the channel constitutively, whereas the N-lobe interacts with the S4-S5 linker in a Ca-dependent manner. The S4-S5 linker, which contains two distinct helices, undergoes conformational changes upon CaM binding to open the channel pore. These structures reveal the gating mechanism of SK channels and provide a basis for understanding SK channel pharmacology. | |||||||||
History |
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Structure visualization
Movie |
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Structure viewer | EM map: ![]() ![]() ![]() |
Supplemental images |
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Downloads & links
-EMDB archive
Map data | ![]() | 96.3 MB | ![]() | |
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Header (meta data) | ![]() ![]() | 13.8 KB 13.8 KB | Display Display | ![]() |
Images | ![]() | 160.3 KB | ||
Filedesc metadata | ![]() | 5.3 KB | ||
Others | ![]() | 49.9 MB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 6cnoMC ![]() 7537C ![]() 7538C ![]() 6cnmC ![]() 6cnnC C: citing same article ( M: atomic model generated by this map |
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Similar structure data |
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Links
EMDB pages | ![]() ![]() |
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Related items in Molecule of the Month |
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Map
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Annotation | human SK4/calmodulin channel complex in the Ca2+ bound state II: sharpened, filtered map | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 1.03 Å | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Density |
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Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Details | EMDB XML:
CCP4 map header:
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-Supplemental data
-Additional map: human SK4/calmodulin channel complex in the Ca2+ bound...
File | emd_7539_additional.map | ||||||||||||
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Annotation | human SK4/calmodulin channel complex in the Ca2+ bound state II: unsharpened, filtered map | ||||||||||||
Projections & Slices |
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Density Histograms |
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Sample components
-Entire : human SK4/calmodulin channel complex
Entire | Name: human SK4/calmodulin channel complex |
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Components |
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-Supramolecule #1: human SK4/calmodulin channel complex
Supramolecule | Name: human SK4/calmodulin channel complex / type: complex / ID: 1 / Parent: 0 / Macromolecule list: #1-#2 |
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Source (natural) | Organism: ![]() ![]() |
-Macromolecule #1: Intermediate conductance calcium-activated potassium channel protein 4
Macromolecule | Name: Intermediate conductance calcium-activated potassium channel protein 4 type: protein_or_peptide / ID: 1 / Number of copies: 4 / Enantiomer: LEVO |
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Source (natural) | Organism: ![]() ![]() |
Molecular weight | Theoretical: 47.758496 KDa |
Recombinant expression | Organism: ![]() ![]() |
Sequence | String: MGGDLVLGLG ALRRRKRLLE QEKSLAGWAL VLAGTGIGLM VLHAEMLWFG GCSWALYLFL VKCTISISTF LLLCLIVAFH AKEVQLFMT DNGLRDWRVA LTGRQAAQIV LELVVCGLHP APVRGPPCVQ DLGAPLTSPQ PWPGFLGQGE ALLSLAMLLR L YLVPRAVL ...String: MGGDLVLGLG ALRRRKRLLE QEKSLAGWAL VLAGTGIGLM VLHAEMLWFG GCSWALYLFL VKCTISISTF LLLCLIVAFH AKEVQLFMT DNGLRDWRVA LTGRQAAQIV LELVVCGLHP APVRGPPCVQ DLGAPLTSPQ PWPGFLGQGE ALLSLAMLLR L YLVPRAVL LRSGVLLNAS YRSIGALNQV RFRHWFVAKL YMNTHPGRLL LGLTLGLWLT TAWVLSVAER QAVNATGHLS DT LWLIPIT FLTIGYGDVV PGTMWGKIVC LCTGVMGVCC TALLVAVVAR KLEFNKAEKH VHNFMMDIQY TKEMKESAAR VLQ EAWMFY KHTRRKESHA ARRHQRKLLA AINAFRQVRL KHRKLREQVN SMVDISKMHM ILYDLQQNLS SSHRALEKQI DTLA GKLDA LTELLSTALG PRQLPEPSQQ SK UniProtKB: Intermediate conductance calcium-activated potassium channel protein 4 |
-Macromolecule #2: Calmodulin-1
Macromolecule | Name: Calmodulin-1 / type: protein_or_peptide / ID: 2 / Number of copies: 4 / Enantiomer: LEVO |
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Source (natural) | Organism: ![]() ![]() |
Molecular weight | Theoretical: 16.852545 KDa |
Recombinant expression | Organism: ![]() ![]() |
Sequence | String: MADQLTEEQI AEFKEAFSLF DKDGDGTITT KELGTVMRSL GQNPTEAELQ DMINEVDADG NGTIDFPEFL TMMARKMKDT DSEEEIREA FRVFDKDGNG YISAAELRHV MTNLGEKLTD EEVDEMIREA DIDGDGQVNY EEFVQMMTAK UniProtKB: ![]() |
-Macromolecule #3: CALCIUM ION
Macromolecule | Name: CALCIUM ION / type: ligand / ID: 3 / Number of copies: 12 / Formula: CA |
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Molecular weight | Theoretical: 40.078 Da |
-Experimental details
-Structure determination
Method | ![]() |
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Aggregation state | particle |
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Sample preparation
Buffer | pH: 8 |
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Vitrification | Cryogen name: ETHANE |
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Electron microscopy
Microscope | FEI TITAN KRIOS |
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Electron beam | Acceleration voltage: 300 kV / Electron source: ![]() |
Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD![]() |
Image recording | Film or detector model: GATAN K2 SUMMIT (4k x 4k) / Average electron dose: 75.0 e/Å2 |
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Image processing
Startup model | Type of model: OTHER |
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Initial angle assignment | Type: PROJECTION MATCHING |
Final angle assignment | Type: PROJECTION MATCHING |
Final reconstruction | Applied symmetry - Point group: C4 (4 fold cyclic![]() |