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- PDB-9y5q: Cryo EM structure of KCa3.1_R355K_I/calmodulin channel in complex... -

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Basic information

Entry
Database: PDB / ID: 9y5q
TitleCryo EM structure of KCa3.1_R355K_I/calmodulin channel in complex with rimtuzalcap
Components
  • Calmodulin-1
  • Intermediate conductance calcium-activated potassium channel protein 4
KeywordsTRANSPORT PROTEIN / Ion channel / Intermediate conductance calcium-activated potassium channel / Calmodulin binding protein
Function / homology
Function and homology information


intermediate conductance calcium-activated potassium channel activity / saliva secretion / small conductance calcium-activated potassium channel activity / Ca2+ activated K+ channels / stabilization of membrane potential / macropinocytosis / calcium-activated potassium channel activity / regulation of calcium ion import across plasma membrane / positive regulation of potassium ion transmembrane transport / cell volume homeostasis ...intermediate conductance calcium-activated potassium channel activity / saliva secretion / small conductance calcium-activated potassium channel activity / Ca2+ activated K+ channels / stabilization of membrane potential / macropinocytosis / calcium-activated potassium channel activity / regulation of calcium ion import across plasma membrane / positive regulation of potassium ion transmembrane transport / cell volume homeostasis / CaM pathway / Cam-PDE 1 activation / Sodium/Calcium exchangers / Calmodulin induced events / Reduction of cytosolic Ca++ levels / Activation of Ca-permeable Kainate Receptor / CREB1 phosphorylation through the activation of CaMKII/CaMKK/CaMKIV cascasde / Loss of phosphorylation of MECP2 at T308 / phospholipid translocation / CREB1 phosphorylation through the activation of Adenylate Cyclase / CaMK IV-mediated phosphorylation of CREB / PKA activation / negative regulation of high voltage-gated calcium channel activity / Glycogen breakdown (glycogenolysis) / CLEC7A (Dectin-1) induces NFAT activation / Activation of RAC1 downstream of NMDARs / negative regulation of ryanodine-sensitive calcium-release channel activity / organelle localization by membrane tethering / mitochondrion-endoplasmic reticulum membrane tethering / autophagosome membrane docking / negative regulation of calcium ion export across plasma membrane / regulation of cardiac muscle cell action potential / presynaptic endocytosis / Synthesis of IP3 and IP4 in the cytosol / regulation of cell communication by electrical coupling involved in cardiac conduction / Phase 0 - rapid depolarisation / positive regulation of T cell receptor signaling pathway / calcineurin-mediated signaling / Negative regulation of NMDA receptor-mediated neuronal transmission / Unblocking of NMDA receptors, glutamate binding and activation / RHO GTPases activate PAKs / Uptake and function of anthrax toxins / Ion transport by P-type ATPases / regulation of ryanodine-sensitive calcium-release channel activity / Long-term potentiation / protein phosphatase activator activity / Calcineurin activates NFAT / Regulation of MECP2 expression and activity / DARPP-32 events / Smooth Muscle Contraction / immune system process / detection of calcium ion / regulation of cardiac muscle contraction / potassium channel activity / catalytic complex / RHO GTPases activate IQGAPs / regulation of cardiac muscle contraction by regulation of the release of sequestered calcium ion / cellular response to interferon-beta / calcium channel inhibitor activity / Activation of AMPK downstream of NMDARs / Protein methylation / presynaptic cytosol / regulation of release of sequestered calcium ion into cytosol by sarcoplasmic reticulum / Ion homeostasis / eNOS activation / titin binding / Tetrahydrobiopterin (BH4) synthesis, recycling, salvage and regulation / sperm midpiece / regulation of calcium-mediated signaling / voltage-gated potassium channel complex / potassium ion transmembrane transport / calcium channel complex / FCERI mediated Ca+2 mobilization / substantia nigra development / regulation of heart rate / Ras activation upon Ca2+ influx through NMDA receptor / FCGR3A-mediated IL10 synthesis / Antigen activates B Cell Receptor (BCR) leading to generation of second messengers / calyx of Held / adenylate cyclase activator activity / sarcomere / VEGFR2 mediated cell proliferation / protein serine/threonine kinase activator activity / regulation of cytokinesis / VEGFR2 mediated vascular permeability / positive regulation of protein secretion / spindle microtubule / positive regulation of receptor signaling pathway via JAK-STAT / Translocation of SLC2A4 (GLUT4) to the plasma membrane / calcium channel regulator activity / establishment of localization in cell / RAF activation / defense response / Transcriptional activation of mitochondrial biogenesis / response to calcium ion / cellular response to type II interferon / potassium ion transport / Stimuli-sensing channels / G2/M transition of mitotic cell cycle / ruffle membrane
Similarity search - Function
Calmodulin-binding domain / Potassium channel, calcium-activated, SK / SK, calmodulin-binding domain superfamily / Calmodulin binding domain / Calcium-activated SK potassium channel / Calmodulin binding domain / Potassium channel domain / Ion channel / : / EF-hand domain pair ...Calmodulin-binding domain / Potassium channel, calcium-activated, SK / SK, calmodulin-binding domain superfamily / Calmodulin binding domain / Calcium-activated SK potassium channel / Calmodulin binding domain / Potassium channel domain / Ion channel / : / EF-hand domain pair / EF-hand, calcium binding motif / EF-Hand 1, calcium-binding site / EF-hand calcium-binding domain. / EF-hand calcium-binding domain profile. / EF-hand domain / EF-hand domain pair
Similarity search - Domain/homology
: / : / Intermediate conductance calcium-activated potassium channel protein 4 / Calmodulin-1
Similarity search - Component
Biological speciesHomo sapiens (human)
MethodELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 4.73 Å
AuthorsNam, Y.W. / Zhang, M.
Funding support United States, 4items
OrganizationGrant numberCountry
American Heart Association23AIREA1039423 United States
American Heart Association24CDA1260237 United States
National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS)4R33 NS101182-03 United States
National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS)R15 NS130420-01A1 United States
CitationJournal: To Be Published
Title: Structural basis for the subtype-selectivity of KCa2.2 channel activators.
Authors: Nam, Y.W. / Zhang, M.
History
DepositionSep 5, 2025Deposition site: RCSB / Processing site: RCSB
Revision 1.0Oct 15, 2025Provider: repository / Type: Initial release
Revision 1.0Oct 15, 2025Data content type: EM metadata / Data content type: EM metadata / Provider: repository / Type: Initial release
Revision 1.0Oct 15, 2025Data content type: Half map / Part number: 1 / Data content type: Half map / Provider: repository / Type: Initial release
Revision 1.0Oct 15, 2025Data content type: Half map / Part number: 2 / Data content type: Half map / Provider: repository / Type: Initial release
Revision 1.0Oct 15, 2025Data content type: Image / Data content type: Image / Provider: repository / Type: Initial release
Revision 1.0Oct 15, 2025Data content type: Primary map / Data content type: Primary map / Provider: repository / Type: Initial release
Revision 1.1Nov 19, 2025Group: Data collection / Derived calculations / Structure summary
Category: chem_comp / em_admin ...chem_comp / em_admin / entity / pdbx_entity_nonpoly
Item: _chem_comp.name / _chem_comp.pdbx_synonyms ..._chem_comp.name / _chem_comp.pdbx_synonyms / _em_admin.last_update / _entity.pdbx_description / _pdbx_entity_nonpoly.name
Revision 1.1Nov 19, 2025Data content type: EM metadata / Data content type: EM metadata / EM metadata / Group: Experimental summary / Structure summary / Data content type: EM metadata / EM metadata / Category: em_admin / entity
Data content type: EM metadata / EM metadata ...EM metadata / EM metadata / EM metadata / EM metadata
Item: _chem_comp.name / _chem_comp.pdbx_synonyms ..._chem_comp.name / _chem_comp.pdbx_synonyms / _em_admin.last_update / _entity.pdbx_description

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Structure visualization

Structure viewerMolecule:
MolmilJmol/JSmol

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Assembly

Deposited unit
A: Intermediate conductance calcium-activated potassium channel protein 4
B: Intermediate conductance calcium-activated potassium channel protein 4
C: Intermediate conductance calcium-activated potassium channel protein 4
D: Intermediate conductance calcium-activated potassium channel protein 4
E: Calmodulin-1
F: Calmodulin-1
G: Calmodulin-1
H: Calmodulin-1
hetero molecules


Theoretical massNumber of molelcules
Total (without water)238,08017
Polymers236,3678
Non-polymers1,7139
Water00
1


  • Idetical with deposited unit
  • defined by author
  • Evidence: electron microscopy, not applicable
TypeNameSymmetry operationNumber
identity operation1_5551

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Components

#1: Protein
Intermediate conductance calcium-activated potassium channel protein 4 / SKCa 4 / SKCa4 / hSK4 / Gardos channel / IKCa1 / hIK1 / KCa3.1 / Putative Gardos channel / hKCa4


Mass: 42570.617 Da / Num. of mol.: 4 / Mutation: R355K
Source method: isolated from a genetically manipulated source
Source: (gene. exp.) Homo sapiens (human) / Gene: KCNN4, IK1, IKCA1, KCA4, SK4 / Production host: Homo sapiens (human) / References: UniProt: O15554
#2: Protein
Calmodulin-1


Mass: 16521.094 Da / Num. of mol.: 4
Source method: isolated from a genetically manipulated source
Source: (gene. exp.) Homo sapiens (human) / Gene: CALM1, CALM, CAM, CAM1 / Production host: Homo sapiens (human) / References: UniProt: P0DP23
#3: Chemical ChemComp-K / POTASSIUM ION


Mass: 39.098 Da / Num. of mol.: 1 / Source method: obtained synthetically / Formula: K / Feature type: SUBJECT OF INVESTIGATION
#4: Chemical
ChemComp-A1B92 / Rimtuzalcap / N-(4,4-difluorocyclohexyl)-2-(3-methyl-1H-pyrazol-1-yl)-6-(morpholin-4-yl)pyrimidin-4-amine


Mass: 378.420 Da / Num. of mol.: 4 / Source method: obtained synthetically / Formula: C18H24F2N6O / Feature type: SUBJECT OF INVESTIGATION
#5: Chemical
ChemComp-CA / CALCIUM ION


Mass: 40.078 Da / Num. of mol.: 4 / Source method: obtained synthetically / Formula: Ca / Feature type: SUBJECT OF INVESTIGATION
Has ligand of interestY
Has protein modificationN

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Experimental details

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Experiment

ExperimentMethod: ELECTRON MICROSCOPY
EM experimentAggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction

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Sample preparation

ComponentName: Human KCa3.1_R355K_I/calmodulin channel in complex with rimtuzalcap
Type: COMPLEX / Entity ID: #1-#2 / Source: RECOMBINANT
Molecular weightValue: 0.23166 MDa / Experimental value: NO
Source (natural)Organism: Homo sapiens (human)
Source (recombinant)Organism: Homo sapiens (human) / Strain: HEK293s / Cell: HEK293 / Plasmid: pGEBacMam
Buffer solutionpH: 8
SpecimenConc.: 2 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES
VitrificationCryogen name: ETHANE

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Electron microscopy imaging

Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company
MicroscopyModel: TFS KRIOS
Electron gunElectron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM
Electron lensMode: BRIGHT FIELD / Nominal defocus max: 2200 nm / Nominal defocus min: 600 nm
Specimen holderSpecimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER
Image recordingElectron dose: 50 e/Å2 / Film or detector model: FEI FALCON IV (4k x 4k)

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Processing

EM software
IDNameVersionCategory
1cryoSPARCparticle selection
7Coot0.9.8.95 ELmodel fitting
9PHENIX1.21.1_5286model refinement
13cryoSPARC3D reconstruction
CTF correctionType: PHASE FLIPPING AND AMPLITUDE CORRECTION
3D reconstructionResolution: 4.73 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 77867 / Symmetry type: POINT
RefinementHighest resolution: 4.73 Å
Stereochemistry target values: REAL-SPACE (WEIGHTED MAP SUM AT ATOM CENTERS)
Refine LS restraints
Refine-IDTypeDev idealNumber
ELECTRON MICROSCOPYf_bond_d0.00215398
ELECTRON MICROSCOPYf_angle_d0.63920879
ELECTRON MICROSCOPYf_dihedral_angle_d5.5092221
ELECTRON MICROSCOPYf_chiral_restr0.0372468
ELECTRON MICROSCOPYf_plane_restr0.0032625

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