Structural Basis for Ca2+ Selectivity of a Voltage-gated Calcium Channel

Experimental Data Snapshot

  • Resolution: 3.40 Å
  • R-Value Free: 0.313 
  • R-Value Work: 0.280 
  • R-Value Observed: 0.281 

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Structural basis for Ca2+ selectivity of a voltage-gated calcium channel.

Tang, L.Gamal El-Din, T.M.Payandeh, J.Martinez, G.Q.Heard, T.M.Scheuer, T.Zheng, N.Catterall, W.A.

(2014) Nature 505: 56-61

  • DOI: https://doi.org/10.1038/nature12775
  • Primary Citation of Related Structures:  
    4MS2, 4MTF, 4MTG, 4MTO, 4MVM, 4MVO, 4MVQ, 4MVR, 4MVS, 4MVU, 4MVZ, 4MW3, 4MW8

  • PubMed Abstract: 

    Voltage-gated calcium (CaV) channels catalyse rapid, highly selective influx of Ca(2+) into cells despite a 70-fold higher extracellular concentration of Na(+). How CaV channels solve this fundamental biophysical problem remains unclear. Here we report physiological and crystallographic analyses of a calcium selectivity filter constructed in the homotetrameric bacterial NaV channel NaVAb. Our results reveal interactions of hydrated Ca(2+) with two high-affinity Ca(2+)-binding sites followed by a third lower-affinity site that would coordinate Ca(2+) as it moves inward. At the selectivity filter entry, Site 1 is formed by four carboxyl side chains, which have a critical role in determining Ca(2+) selectivity. Four carboxyls plus four backbone carbonyls form Site 2, which is targeted by the blocking cations Cd(2+) and Mn(2+), with single occupancy. The lower-affinity Site 3 is formed by four backbone carbonyls alone, which mediate exit into the central cavity. This pore architecture suggests a conduction pathway involving transitions between two main states with one or two hydrated Ca(2+) ions bound in the selectivity filter and supports a 'knock-off' mechanism of ion permeation through a stepwise-binding process. The multi-ion selectivity filter of our CaVAb model establishes a structural framework for understanding the mechanisms of ion selectivity and conductance by vertebrate CaV channels.

  • Organizational Affiliation

    1] Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA [2] Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Ion transport protein
A, B, C, D
237Aliarcobacter butzleri RM4018Mutation(s): 0 
Gene Names: Abu_1752
Membrane Entity: Yes 
Find proteins for A8EVM5 (Aliarcobacter butzleri (strain RM4018))
Explore A8EVM5 
Go to UniProtKB:  A8EVM5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA8EVM5
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on PX4

Download Ideal Coordinates CCD File 
G [auth A]
H [auth A]
I [auth A]
J [auth A]
K [auth B]
G [auth A],
H [auth A],
I [auth A],
J [auth A],
K [auth B],
L [auth B],
M [auth B],
N [auth B],
O [auth C],
P [auth C],
Q [auth C],
R [auth C],
S [auth C],
T [auth D],
U [auth D],
V [auth D]
C36 H73 N O8 P
Query on CA

Download Ideal Coordinates CCD File 
E [auth A],
F [auth A]
Experimental Data & Validation

Experimental Data

  • Resolution: 3.40 Å
  • R-Value Free: 0.313 
  • R-Value Work: 0.280 
  • R-Value Observed: 0.281 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 177.78α = 90
b = 177.725β = 132.79
c = 130.82γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
PHENIXmodel building
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-11-27
    Type: Initial release
  • Version 1.1: 2013-12-18
    Changes: Database references
  • Version 1.2: 2014-01-15
    Changes: Database references
  • Version 1.3: 2014-11-12
    Changes: Structure summary
  • Version 1.4: 2024-02-28
    Changes: Data collection, Database references, Derived calculations