PDBsum entry 3ij4

Transport protein

PDB id: 3ij4

Contents

Protein chain

406 a.a. *

Metals

_CS ×4

_CL

Waters ×54

* Residue conservation analysis

PDB id:

3ij4

Name:

Transport protein

Title:

Cesium sites in the crystal structure of a functional acid sensing ion channel in the desensitized state

Structure:

Amiloride-sensitive cation channel 2, neuronal. Chain: a. Synonym: acid-sensing ion channel 1. Engineered: yes

Source:

Gallus gallus. Bantam,chickens. Organism_taxid: 9031. Gene: accn2, asic1. Expressed in: spodoptera frugiperda. Expression_system_taxid: 7108.

Resolution:

3.00Å R-factor: 0.225 R-free: 0.272

Authors:

E.B.Gonzales,E.Gouaux

Key ref:

E.B.Gonzales et al. (2009). Pore architecture and ion sites in acid-sensing ion channels and P2X receptors. Nature, 460, 599-604. PubMed id: 19641589 DOI: 10.1038/nature08218

Date:

03-Aug-09 Release date: 10-Nov-09

Protein chain

Q1XA76  (ASIC1_CHICK) -  Acid-sensing ion channel 1 from Gallus gallus

Seq: 527 a.a.

Struc: 406 a.a.

DOI no: 10.1038/nature08218

Nature 460:599-604 (2009)

PubMed id: 19641589

Pore architecture and ion sites in acid-sensing ion channels and P2X receptors.

E.B.Gonzales, T.Kawate, E.Gouaux.

ABSTRACT

Acid-sensing ion channels are proton-activated, sodium-selective channels composed of three subunits, and are members of the superfamily of epithelial sodium channels, mechanosensitive and FMRF-amide peptide-gated ion channels. These ubiquitous eukaryotic ion channels have essential roles in biological activities as diverse as sodium homeostasis, taste and pain. Despite their crucial roles in biology and their unusual trimeric subunit stoichiometry, there is little knowledge of the structural and chemical principles underlying their ion channel architecture and ion-binding sites. Here we present the structure of a functional acid-sensing ion channel in a desensitized state at 3 A resolution, the location and composition of the approximately 8 A 'thick' desensitization gate, and the trigonal antiprism coordination of caesium ions bound in the extracellular vestibule. Comparison of the acid-sensing ion channel structure with the ATP-gated P2X(4) receptor reveals similarity in pore architecture and aqueous vestibules, suggesting that there are unanticipated yet common structural and mechanistic principles.

Selected figure(s)

Figure 2.
Figure 2: Structure of ASIC1mfc. a, View of the functional ASIC1mfc trimer. Chloride ions are green spheres. The 'thumb', 'finger' and wrist regions are labelled. Grey bars suggest the boundaries of the outer (out) and inner (in) leaflets of the membrane bilayer. b, A vertical slice through a solvent-accessible surface representation of the transmembrane domain, the extracellular vestibule and fenestrations. One of the three equivalent fenestrations is indicated by an arrow. Asp 433 defines the bottom of the extracellular vestibule. c, Key interactions between symmetry-related Asp 433 carboxyl and Tyr 425 hydroxyl groups.

Figure 4.
Figure 4: Cs^+-binding sites. a, Stereo image of the electron density peaks (3.5 ) from anomalous difference Fourier maps calculated using diffraction data measured from crystals soaked in CsCl. b, Key interactions between Cs^+ ions at sites 1 and 2 with the main-chain and side-chain oxygen atoms of Gly 432 and Asp 433, respectively. c, Stick representation of ASIC1mfc interaction with Cs^+ at site 2. d, Trigonal antiprism coordination of the Cs^+ ion by the Gly 432 carbonyl and Asp 433 carboxyl oxygens. Oxygen atoms (red spheres) form the vertices, whereas solid lines represent the sides of each of the two staggered triangles of the antiprism.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2009, 460, 599-604) copyright 2009.

Figures were selected by an automated process.