8FQ3

LBD conformation 2 (LBDconf2) of GluA2 flip Q isoform N619K mutant of AMPA receptor in complex with gain-of-function TARP gamma-2, with 10mM CaCl2, 150mM NaCl, 1mM MgCl2, 330uM CTZ, and 100mM glutamate (Open-CaNaMg/N619K)

Summary for 8FQ3

• Entry DOI: 10.2210/pdb8fq3/pdb
• EMDB information: 29369 29376
• Descriptor: Glutamate receptor 2, GLUTAMIC ACID, CYCLOTHIAZIDE, ... (4 entities in total)
• Functional Keywords: ionotropic glutamate receptor, ligand gated ion channel, ampa receptor, tarp gamma-2, transport protein
• Biological source: Rattus norvegicus (Norway rat)
• Total number of polymer chains: 4
• Total formula weight: 400446.18

Authors

Nakagawa, T. (deposition date: 2023-01-05, release date: 2024-02-28, Last modification date: 2024-10-16)

Primary citation

Nakagawa, T.,Wang, X.T.,Miguez-Cabello, F.J.,Bowie, D.
The open gate of the AMPA receptor forms a Ca 2+ binding site critical in regulating ion transport.
Nat.Struct.Mol.Biol., 31:688-700, 2024

PubMed Abstract: Alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid receptors (AMPARs) are cation-selective ion channels that mediate most fast excitatory neurotransmission in the brain. Although their gating mechanism has been studied extensively, understanding how cations traverse the pore has remained elusive. Here we investigated putative ion and water densities in the open pore of Ca-permeable AMPARs (rat GRIA2 flip-Q isoform) at 2.3-2.6 Å resolution. We show that the ion permeation pathway attains an extracellular Ca binding site (site-G) when the channel gate moves into the open configuration. Site-G is highly selective for Ca over Na, favoring the movement of Ca into the selectivity filter of the pore. Seizure-related N619K mutation, adjacent to site-G, promotes channel opening but attenuates Ca binding and thus diminishes Ca permeability. Our work identifies the importance of site-G, which coordinates with the Q/R site of the selectivity filter to ensure the preferential transport of Ca through the channel pore.

PubMed: 38409505
DOI: 10.1038/s41594-024-01228-3

Experimental method

ELECTRON MICROSCOPY (3.17 Å)