PDBsum entry 4x5t

Signaling protein

PDB id: 4x5t

Contents

Protein chains

308 a.a.

Ligands

ACT ×5

Metals

_NI ×6

_CL ×6

PDB id:

4x5t

Name:

Signaling protein

Title:

Alpha 1 glycine receptor transmembrane structure fused to the extracellular domain of glic

Structure:

Proton-gated ion channel,glra1 protein,glra1 protein. Chain: a, b, c, d, e. Synonym: glic,ligand-gated ion channel,lgic. Engineered: yes

Source:

Gloeobacter violaceus, homo sapiens. Human. Organism_taxid: 251221, 9606. Strain: pcc 7421. Gene: glvi, glr4197, glra1. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

3.50Å R-factor: 0.254 R-free: 0.270

Authors:

L.Sauguet,P.J.Corringer,C.Huon,M.Delarue

Key ref:

G.Moraga-Cid et al. (2015). Allosteric and hyperekplexic mutant phenotypes investigated on an α1 glycine receptor transmembrane structure. Proc Natl Acad Sci U S A, 112, 2865-2870. PubMed id: 25730860 DOI: 10.1073/pnas.1417864112

Date:

05-Dec-14 Release date: 25-Feb-15

Protein chains

P23415  (GLRA1_HUMAN) -  Glycine receptor subunit alpha-1 from Homo sapiens

Seq: 457 a.a.

Struc: 308 a.a.*

Protein chains

Q7NDN8  (GLIC_GLOVI) -  Proton-gated ion channel from Gloeobacter violaceus (strain ATCC 29082 / PCC 7421)

Seq: 359 a.a.

Struc: 308 a.a.*

* PDB and UniProt seqs differ at 236 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1073/pnas.1417864112

Proc Natl Acad Sci U S A 112:2865-2870 (2015)

PubMed id: 25730860

Allosteric and hyperekplexic mutant phenotypes investigated on an α1 glycine receptor transmembrane structure.

G.Moraga-Cid, L.Sauguet, C.Huon, L.Malherbe, C.Girard-Blanc, S.Petres, S.Murail, A.Taly, M.Baaden, M.Delarue, P.J.Corringer.

ABSTRACT

The glycine receptor (GlyR) is a pentameric ligand-gated ion channel (pLGIC) mediating inhibitory transmission in the nervous system. Its transmembrane domain (TMD) is the target of allosteric modulators such as general anesthetics and ethanol and is a major locus for hyperekplexic congenital mutations altering the allosteric transitions of activation or desensitization. We previously showed that the TMD of the human α1GlyR could be fused to the extracellular domain of GLIC, a bacterial pLGIC, to form a functional chimera called Lily. Here, we overexpress Lily in Schneider 2 insect cells and solve its structure by X-ray crystallography at 3.5 Å resolution. The TMD of the α1GlyR adopts a closed-channel conformation involving a single ring of hydrophobic residues at the center of the pore. Electrophysiological recordings show that the phenotypes of key allosteric mutations of the α1GlyR, scattered all along the pore, are qualitatively preserved in this chimera, including those that confer decreased sensitivity to agonists, constitutive activity, decreased activation kinetics, or increased desensitization kinetics. Combined structural and functional data indicate a pore-opening mechanism for the α1GlyR, suggesting a structural explanation for the effect of some key hyperekplexic allosteric mutations. The first X-ray structure of the TMD of the α1GlyR solved here using GLIC as a scaffold paves the way for mechanistic investigation and design of allosteric modulators of a human receptor.