3UKM

Crystal structure of the human two pore domain potassium ion channel K2P1 (TWIK-1)

• PDB DOI: https://doi.org/10.2210/pdb3UKM/pdb

• Classification: MEMBRANE PROTEIN
• Organism(s): Homo sapiens
• Expression System: Komagataella pastoris
• Mutation(s): Yes 
• Membrane Protein: Yes  OPMPDBTMMemProtMDmpstruc


• Deposited: 2011-11-09 Released: 2012-02-08 
• Deposition Author(s): Long, S.B., Miller, A.N.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 3.40 Å
• R-Value Free: 0.279 
• R-Value Work: 0.273 
• R-Value Observed: 0.273 

Literature

Crystal structure of the human two-pore domain potassium channel K2P1.

Miller, A.N., Long, S.B.

(2012) Science 335: 432-436

• PubMed: 22282804 
• DOI: https://doi.org/10.1126/science.1213274
• Primary Citation of Related Structures:  
  3UKM


• PubMed Abstract: 
  

  Two-pore domain potassium (K(+)) channels (K2P channels) control the negative resting potential of eukaryotic cells and regulate cell excitability by conducting K(+) ions across the plasma membrane. Here, we present the 3.4 angstrom resolution crystal structure of a human K2P channel, K2P1 (TWIK-1). Unlike other K(+) channel structures, K2P1 is dimeric. An extracellular cap domain located above the selectivity filter forms an ion pathway in which K(+) ions flow through side portals. Openings within the transmembrane region expose the pore to the lipid bilayer and are filled with electron density attributable to alkyl chains. An interfacial helix appears structurally poised to affect gating. The structure lays a foundation to further investigate how K2P channels are regulated by diverse stimuli.

---

Organizational Affiliation: 

Structural Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

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

Biological Assembly 2  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 2 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 128.66 kDa 
• Atom Count: 7,606 
• Modelled Residue Count: 1,008 
• Deposited Residue Count: 1,120 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Potassium channel subfamily K member 1	A, B, C, D	280	Homo sapiens	Mutation(s): 3  Gene Names: HOHO1, K2P1 (TWIK-1), KCNK1, KCNO1, TWIK1 Membrane Entity: Yes
UniProt & NIH Common Fund Data Resources
Find proteins for O00180 (Homo sapiens) Explore O00180  Go to UniProtKB:  O00180
PHAROS:  O00180 GTEx:  ENSG00000135750

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
UND	E [auth A], K [auth B], L [auth C], R [auth D]	UNDECANE C11 H24 RSJKGSCJYJTIGS-UHFFFAOYSA-N
K	F [auth A], G [auth A], H [auth A], I [auth A], J [auth A], M [auth C], N [auth C], O [auth C], P [auth C], Q [auth C]	POTASSIUM ION K NPYPAHLBTDXSSS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 3.40 Å
• R-Value Free: 0.279 
• R-Value Work: 0.273 
• R-Value Observed: 0.273 
• Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 82.08	α = 90
b = 123.171	β = 94.91
c = 119.305	γ = 90

Software Package:

Software Name	Purpose
CBASS	data collection
CNS	refinement
HKL-3000	data reduction
HKL-3000	data scaling

Structure Validation

Entry History 

Deposition Data

• Released Date: 2012-02-08 
Deposition Author(s): Long, S.B., Miller, A.N.

Revision History  

• Version 1.0: 2012-02-08
  Type: Initial release
  
• Version 1.1: 2024-10-30
  Changes: Data collection, Database references, Derived calculations, Structure summary