9ZPT | pdb_00009zpt

Cryo-EM structure of KCa3.1_II/calmodulin channel in complex with SKA31.

• PDB DOI: https://doi.org/10.2210/pdb9ZPT/pdb
• EM Map EMD-74533: EMDB EMDataResource

• Classification: MEMBRANE PROTEIN
• Organism(s): Homo sapiens
• Expression System: Homo sapiens
• Mutation(s): No 


• Deposited: 2025-12-17 Released: 2026-01-14 
• Deposition Author(s): Nam, Y.W., Ramanishka, A., Zhang, M.
• Funding Organization(s): American Heart Association, National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS)

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 3.39 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

Structural basis for the subtype-selective activation of KCa3.1 channels.

Nam, Y.W., Ramanishka, A., Zhang, M.

To be published.

Biological Assembly 1  

Global Symmetry: Cyclic - C4  (Explore in 3D)
Global Stoichiometry: Hetero 8-mer - A4B4 

Biological assembly 1 assigned by authors and generated by (software)

Biological Assembly Evidence: electron microscopy

Macromolecule Content 

• Total Structure Weight: 184.55 kDa 
• Atom Count: 12,016 
• Modeled Residue Count: 1,628 
• Deposited Residue Count: 1,628 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Intermediate conductance calcium-activated potassium channel protein 4	A, B, C, D	340	Homo sapiens	Mutation(s): 0  Gene Names: KCNN4, IK1, IKCA1, KCA4, SK4
UniProt & NIH Common Fund Data Resources
Find proteins for O15554 (Homo sapiens) Explore O15554  Go to UniProtKB:  O15554
PHAROS:  O15554 GTEx:  ENSG00000104783

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Calmodulin-1	E, F, G, H	67	Homo sapiens	Mutation(s): 0  Gene Names: CALM1, CALM, CAM, CAM1
UniProt & NIH Common Fund Data Resources
Find proteins for P0DP23 (Homo sapiens) Explore P0DP23  Go to UniProtKB:  P0DP23
PHAROS:  P0DP23 GTEx:  ENSG00000198668

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
K	I [auth A], J [auth A], K [auth A], L [auth A]	POTASSIUM ION K NPYPAHLBTDXSSS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 3.39 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX	1.21.1_5286
RECONSTRUCTION	cryoSPARC

Structure Validation

Entry History & Funding Information

Deposition Data

• Released Date: 2026-01-14 
Deposition Author(s): Nam, Y.W., Ramanishka, A., Zhang, M.

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Funding Organization	Location	Grant Number
American Heart Association	United States	23AIREA1039423
American Heart Association	United States	24CDA1260237
National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS)	United States	4R33 NS101182-03
National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS)	United States	R15 NS130420-01A1

Revision History  

• Version 1.0: 2026-01-14
  Type: Initial release