9MA5 | pdb_00009ma5

Cryo-EM structure of heteromeric Kir4.1/5.1 potassium channel in complex with spermine

• PDB DOI: https://doi.org/10.2210/pdb9MA5/pdb
• EM Map EMD-63747: EMDB EMDataResource

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


• Deposited: 2025-03-14 Released: 2026-03-18 
• Deposition Author(s): Ning, Y., Ge, J., Yu, J.
• Funding Organization(s): Other government

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 3.18 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

CryoEM structure of a transmembrane protein

Ning, Y., Ge, J., Yu, J.

To be published.

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Hetero 4-mer - A2B2 Pseudo Symmetry: Cyclic - C4  (Explore in 3D)
Pseudo Stoichiometry: Homo 4-mer - A4 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: electron microscopy

Macromolecule Content 

• Total Structure Weight: 156.53 kDa 
• Atom Count: 10,192 
• Modeled Residue Count: 1,266 
• Deposited Residue Count: 1,364 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Inward rectifier potassium channel 16	A, C	337	Homo sapiens	Mutation(s): 0  Gene Names: KCNJ16
UniProt & NIH Common Fund Data Resources
Find proteins for Q9NPI9 (Homo sapiens) Explore Q9NPI9  Go to UniProtKB:  Q9NPI9
PHAROS:  Q9NPI9 GTEx:  ENSG00000153822

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
ATP-sensitive inward rectifier potassium channel 10	B, D	345	Homo sapiens	Mutation(s): 0  Gene Names: KCNJ10
UniProt & NIH Common Fund Data Resources
Find proteins for P78508 (Homo sapiens) Explore P78508  Go to UniProtKB:  P78508
PHAROS:  P78508 GTEx:  ENSG00000177807

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
SPM (Subject of Investigation/LOI)	I [auth B], J [auth D]	SPERMINE C10 H26 N4 PFNFFQXMRSDOHW-UHFFFAOYSA-N
K (Subject of Investigation/LOI)	E [auth A], F [auth A], G [auth B], H [auth B]	POTASSIUM ION K NPYPAHLBTDXSSS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 3.18 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX	1.20.1_4487

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-03-18 
Deposition Author(s): Ning, Y., Ge, J., Yu, J.

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Funding Organization	Location	Grant Number
Other government		LG-QS-202203-05; 22PJ1410300; 32471016

Revision History  

• Version 1.0: 2026-03-18
  Type: Initial release
  
• Version 1.1: 2026-05-13
  Changes: Data collection, Structure summary