[English] 日本語
Yorodumi
- EMDB-74628: Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111. -

+
Open data


ID or keywords:

Loading...

-
Basic information

Entry
Database: EMDB / ID: EMD-74628
TitleCryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111.
Map dataCryo-EM map of KCa2.2/calmodulin channel in complex with SKA111.
Sample
  • Complex: Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111.
    • Protein or peptide: Small conductance calcium-activated potassium channel protein 2
    • Protein or peptide: Calmodulin-1
  • Ligand: POTASSIUM ION
  • Ligand: 5-methylnaphtho[1,2-d][1,3]thiazol-2-amine
  • Ligand: CALCIUM ION
  • Ligand: water
KeywordsIntermediate conductance calcium-activated potassium channel / Ion channel / Calmodulin binding protein / TRANSPORT PROTEIN / MEMBRANE PROTEIN
Function / homology
Function and homology information


small conductance calcium-activated potassium channel activity / Acetylcholine inhibits contraction of outer hair cells / membrane repolarization during atrial cardiac muscle cell action potential / Ca2+ activated K+ channels / calcium-activated potassium channel activity / inward rectifier potassium channel activity / regulation of potassium ion transmembrane transport / CaM pathway / Cam-PDE 1 activation / Sodium/Calcium exchangers ...small conductance calcium-activated potassium channel activity / Acetylcholine inhibits contraction of outer hair cells / membrane repolarization during atrial cardiac muscle cell action potential / Ca2+ activated K+ channels / calcium-activated potassium channel activity / inward rectifier potassium channel activity / regulation of potassium ion transmembrane transport / 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 / CREB1 phosphorylation through the activation of Adenylate Cyclase / negative regulation of high voltage-gated calcium channel activity / PKA activation / CaMK IV-mediated phosphorylation of CREB / 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 / : / autophagosome membrane docking / negative regulation of calcium ion export across plasma membrane / regulation of ryanodine-sensitive calcium-release channel activity / regulation of cardiac muscle cell action potential / presynaptic endocytosis / Synthesis of IP3 and IP4 in the cytosol / Phase 0 - rapid depolarisation / Negative regulation of NMDA receptor-mediated neuronal transmission / Unblocking of NMDA receptors, glutamate binding and activation / RHO GTPases activate PAKs / calcineurin-mediated signaling / regulation of cell communication by electrical coupling involved in cardiac conduction / Ion transport by P-type ATPases / alpha-actinin binding / Uptake and function of anthrax toxins / protein phosphatase activator activity / Long-term potentiation / Calcineurin activates NFAT / Regulation of MECP2 expression and activity / DARPP-32 events / Smooth Muscle Contraction / detection of calcium ion / regulation of cardiac muscle contraction / catalytic complex / RHO GTPases activate IQGAPs / calcium channel inhibitor activity / presynaptic cytosol / Activation of AMPK downstream of NMDARs / cellular response to interferon-beta / regulation of release of sequestered calcium ion into cytosol by sarcoplasmic reticulum / Ion homeostasis / eNOS activation / Protein methylation / Tetrahydrobiopterin (BH4) synthesis, recycling, salvage and regulation / titin binding / regulation of cardiac muscle contraction by regulation of the release of sequestered calcium ion / regulation of calcium-mediated signaling / voltage-gated potassium channel complex / FCERI mediated Ca+2 mobilization / calcium channel complex / potassium ion transmembrane transport / substantia nigra development / FCGR3A-mediated IL10 synthesis / regulation of heart rate / Antigen activates B Cell Receptor (BCR) leading to generation of second messengers / Ras activation upon Ca2+ influx through NMDA receptor / calyx of Held / adenylate cyclase activator activity / VEGFR2 mediated cell proliferation / VEGFR2 mediated vascular permeability / regulation of cytokinesis / protein serine/threonine kinase activator activity / spindle microtubule / sarcomere / positive regulation of receptor signaling pathway via JAK-STAT / Translocation of SLC2A4 (GLUT4) to the plasma membrane / calcium channel regulator activity / potassium ion transport / Transcriptional activation of mitochondrial biogenesis / RAF activation / response to calcium ion / cellular response to type II interferon / G2/M transition of mitotic cell cycle / Stimuli-sensing channels / Z disc / spindle pole / calcium-dependent protein binding / Signaling by RAF1 mutants / Signaling by moderate kinase activity BRAF mutants / Paradoxical activation of RAF signaling by kinase inactive BRAF / Signaling downstream of RAS mutants / RAS processing / Signaling by BRAF and RAF1 fusions / Platelet degranulation / long-term synaptic potentiation
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
Calmodulin-1 / Small conductance calcium-activated potassium channel protein 2
Similarity search - Component
Biological speciesHomo sapiens (human)
Methodsingle particle reconstruction / cryo EM / Resolution: 3.31 Å
AuthorsNam YW / Ramanishka A / Zhang M
Funding support United States, 4 items
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: Structure / Year: 2026
Title: Structural basis for the subtype-selective activation of K3.1 channels.
Authors: Alena Ramanishka / Joshua A Nasburg / Yang Xu / Xinyi Ma / Reza Mehvar / Meng Cui / Young-Woo Nam / Heike Wulff / Miao Zhang /
Abstract: The intermediate-conductance (K3.1) and the small-conductance (K2.2) Ca-activated K channels share a Ca-calmodulin dependent gating mechanism. We report cryo-electron microscopy structures of K3.1 ...The intermediate-conductance (K3.1) and the small-conductance (K2.2) Ca-activated K channels share a Ca-calmodulin dependent gating mechanism. We report cryo-electron microscopy structures of K3.1 and K2.2 in complex with two benzothiazole-type activators. While SKA-31 is only moderately selective (∼7.3-fold), its derivative SKA-111 exhibits ∼70-fold selectivity for K3.1 over K2.2. SKA-31 and SKA-111 both bind in a pocket at the interface between the SA helix and calmodulin where they allosterically modulate the inner gate of the two channels. SKA-31 binds with comparable energies in the two channels, consistent with its moderate selectivity for K3.1 over K2.2. In the K3.1 structure, the calmodulin helix IV is positioned outward, forming a pocket that more readily accommodates the bulkier SKA-111 that sits deeper inside calmodulin's N-lobe in K3.1 than in K2.2. The resulting higher binding energy explains the improved selectivity of SKA-111 for K3.1 compared to the less selective SKA-31.
History
DepositionDec 20, 2025-
Header (metadata) releaseMay 27, 2026-
Map releaseMay 27, 2026-
UpdateMay 27, 2026-
Current statusMay 27, 2026Processing site: RCSB / Status: Released

-
Structure visualization

Supplemental images

emd_74628.png

Downloads & links

-
Map

FileDownload / File: emd_74628.map.gz / Format: CCP4 / Size: 476.8 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES)
AnnotationCryo-EM map of KCa2.2/calmodulin channel in complex with SKA111.
Projections & slices

Image control

Size
Brightness
Contrast
Others
AxesX (Sec.)Y (Row.)Z (Col.)
0.86 Å/pix.
x 500 pix.
= 430. Å		0.86 Å/pix.
x 500 pix.
= 430. Å		0.86 Å/pix.
x 500 pix.
= 430. Å

Surface

Projections

Slices (1/3)

Slices (1/2)

Slices (2/3)

Images are generated by Spider.

Voxel sizeX=Y=Z: 0.86 Å
Density

Histogram

Histogram (log scale)
Contour LevelBy AUTHOR: 6.5
Minimum - Maximum-35.143749999999997 - 64.557625000000002
Average (Standard dev.)0.00000000000254 (±1.0)
SymmetrySpace group: 1
Details

EMDB XML:

Map geometry
Axis orderZYX
Origin000
Dimensions500500500
Spacing500500500
CellA=B=C: 430.0 Å
α=β=γ: 90.0 °

-
Supplemental data

-
Half map: Cryo-EM half map of KCa2.2/calmodulin channel in complex with SKA111.

Fileemd_74628_half_map_1.map
AnnotationCryo-EM half map of KCa2.2/calmodulin channel in complex with SKA111.
Projections & Slices
AxesZYX

Projections

Slices (1/2)
Density Histograms

Histogram

Histogram (log scale)

-
Half map: Cryo-EM half map of KCa2.2/calmodulin channel in complex with SKA111.

Fileemd_74628_half_map_2.map
AnnotationCryo-EM half map of KCa2.2/calmodulin channel in complex with SKA111.
Projections & Slices
AxesZYX

Projections

Slices (1/2)
Density Histograms

Histogram

Histogram (log scale)

-
Sample components

-
Entire : Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111.

EntireName: Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111.
Components
  • Complex: Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111.
    • Protein or peptide: Small conductance calcium-activated potassium channel protein 2
    • Protein or peptide: Calmodulin-1
  • Ligand: POTASSIUM ION
  • Ligand: 5-methylnaphtho[1,2-d][1,3]thiazol-2-amine
  • Ligand: CALCIUM ION
  • Ligand: water

-
Supramolecule #1: Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111.

SupramoleculeName: Cryo-EM structure of KCa2.2/calmodulin channel in complex with SKA111.
type: complex / ID: 1 / Parent: 0 / Macromolecule list: #1-#2
Source (natural)Organism: Homo sapiens (human)
Molecular weightTheoretical: 229.73 KDa

-
Macromolecule #1: Small conductance calcium-activated potassium channel protein 2

MacromoleculeName: Small conductance calcium-activated potassium channel protein 2
type: protein_or_peptide / ID: 1 / Number of copies: 4 / Enantiomer: LEVO
Source (natural)Organism: Homo sapiens (human)
Molecular weightTheoretical: 41.114754 KDa
Recombinant expressionOrganism: Homo sapiens (human)
SequenceString: IGYKLGHRRA LFEKRKRLSD YALIFGMFGI VVMVIETELS WGAYDKASLY SLALKCLISL STIILLGLII VYHAREIQLF MVDNGADDW RIAMTYERIF FICLEILVCA IHPIPGNYTF TWTARLAFSY APSTTTADVD IILSIPMFLR LYLIARVMLL H SKLFTDAS ...String:
IGYKLGHRRA LFEKRKRLSD YALIFGMFGI VVMVIETELS WGAYDKASLY SLALKCLISL STIILLGLII VYHAREIQLF MVDNGADDW RIAMTYERIF FICLEILVCA IHPIPGNYTF TWTARLAFSY APSTTTADVD IILSIPMFLR LYLIARVMLL H SKLFTDAS SRSIGALNKI NFNTRFVMKT LMTICPGTVL LVFSISLWII AAWTVRACER YHDQQDVTSN FLGAMWLISI TF LSIGYGD MVPNTYCGKG VCLLTGIMGA GCTALVVAVV ARKLELTKAE KHVHNFMMDT QLTKRVKNAA ANVLRETWLI YKN TKLVKK IDHAKVRKHQ RKFLQAIHQL RSVKMEQRKL NDQAN

UniProtKB: Small conductance calcium-activated potassium channel protein 2

-
Macromolecule #2: Calmodulin-1

MacromoleculeName: Calmodulin-1 / type: protein_or_peptide / ID: 2 / Number of copies: 4 / Enantiomer: LEVO
Source (natural)Organism: Homo sapiens (human)
Molecular weightTheoretical: 16.34891 KDa
Recombinant expressionOrganism: Homo sapiens (human)
SequenceString:
DQLTEEQIAE FKEAFSLFDK DGDGTITTKE LGTVMRSLGQ NPTEAELQDM INEVDADGNG TIDFPEFLTM MARKMKDTDS EEEIREAFR VFDKDGNGYI SAAELRHVMT NLGEKLTDEE VDEMIREADI DGDGQVNYEE FVQMM

UniProtKB: Calmodulin-1

-
Macromolecule #3: POTASSIUM ION

MacromoleculeName: POTASSIUM ION / type: ligand / ID: 3 / Number of copies: 2 / Formula: K
Molecular weightTheoretical: 39.098 Da

-
Macromolecule #4: 5-methylnaphtho[1,2-d][1,3]thiazol-2-amine

MacromoleculeName: 5-methylnaphtho[1,2-d][1,3]thiazol-2-amine / type: ligand / ID: 4 / Number of copies: 4 / Formula: A1C3U
Molecular weightTheoretical: 214.286 Da

-
Macromolecule #5: CALCIUM ION

MacromoleculeName: CALCIUM ION / type: ligand / ID: 5 / Number of copies: 12 / Formula: CA
Molecular weightTheoretical: 40.078 Da

-
Macromolecule #6: water

MacromoleculeName: water / type: ligand / ID: 6 / Number of copies: 8 / Formula: HOH
Molecular weightTheoretical: 18.015 Da
Chemical component information

ChemComp-HOH:
WATER

-
Experimental details

-
Structure determination

Methodcryo EM
Processingsingle particle reconstruction
Aggregation stateparticle

-
Sample preparation

Concentration2 mg/mL
BufferpH: 8
VitrificationCryogen name: ETHANE

-
Electron microscopy

MicroscopeTFS KRIOS
Image recordingFilm or detector model: FEI FALCON IV (4k x 4k) / Average electron dose: 50.0 e/Å2
Electron beamAcceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN
Electron opticsIllumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Nominal defocus max: 2.0 µm / Nominal defocus min: 1.0 µm
Sample stageSpecimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER
Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company

-
Image processing

CTF correctionType: PHASE FLIPPING AND AMPLITUDE CORRECTION
Startup modelType of model: PDB ENTRY
PDB model - PDB ID:

8v2g

Final reconstructionResolution.type: BY AUTHOR / Resolution: 3.31 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: cryoSPARC / Number images used: 215183
Initial angle assignmentType: MAXIMUM LIKELIHOOD

+
About Yorodumi

-
News

-
Feb 9, 2022. New format data for meta-information of EMDB entries

New format data for meta-information of EMDB entries

  • Version 3 of the EMDB header file is now the official format.
  • The previous official version 1.9 will be removed from the archive.

Related info.:EMDB header

External links:wwPDB to switch to version 3 of the EMDB data model

-
Aug 12, 2020. Covid-19 info

Covid-19 info

URL: https://pdbj.org/emnavi/covid19.php

New page: Covid-19 featured information page in EM Navigator.

Related info.:Covid-19 info / Mar 5, 2020. Novel coronavirus structure data

+
Mar 5, 2020. Novel coronavirus structure data

Novel coronavirus structure data

Related info.:Yorodumi Speices / Aug 12, 2020. Covid-19 info

External links:COVID-19 featured content - PDBj / Molecule of the Month (242)：Coronavirus Proteases

+
Jan 31, 2019. EMDB accession codes are about to change! (news from PDBe EMDB page)

EMDB accession codes are about to change! (news from PDBe EMDB page)

  • The allocation of 4 digits for EMDB accession codes will soon come to an end. Whilst these codes will remain in use, new EMDB accession codes will include an additional digit and will expand incrementally as the available range of codes is exhausted. The current 4-digit format prefixed with “EMD-” (i.e. EMD-XXXX) will advance to a 5-digit format (i.e. EMD-XXXXX), and so on. It is currently estimated that the 4-digit codes will be depleted around Spring 2019, at which point the 5-digit format will come into force.
  • The EM Navigator/Yorodumi systems omit the EMD- prefix.

Related info.:Q: What is EMD? / ID/Accession-code notation in Yorodumi/EM Navigator

External links:EMDB Accession Codes are Changing Soon! / Contact to PDBj

+
Jul 12, 2017. Major update of PDB

Major update of PDB

  • wwPDB released updated PDB data conforming to the new PDBx/mmCIF dictionary.
  • This is a major update changing the version number from 4 to 5, and with Remediation, in which all the entries are updated.
  • In this update, many items about electron microscopy experimental information are reorganized (e.g. em_software).
  • Now, EM Navigator and Yorodumi are based on the updated data.

External links:wwPDB Remediation / Enriched Model Files Conforming to OneDep Data Standards Now Available in the PDB FTP Archive

-
Yorodumi

Thousand views of thousand structures

  • Yorodumi is a browser for structure data from EMDB, PDB, SASBDB, etc.
  • This page is also the successor to EM Navigator detail page, and also detail information page/front-end page for Omokage search.
  • The word "yorodu" (or yorozu) is an old Japanese word meaning "ten thousand". "mi" (miru) is to see.

Related info.:EMDB / PDB / SASBDB / Comparison of 3 databanks / Yorodumi Search / Aug 31, 2016. New EM Navigator & Yorodumi / Yorodumi Papers / Jmol/JSmol / Function and homology information / Changes in new EM Navigator and Yorodumi

Read more