Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1999 May 14;288(4):765-86.
doi: 10.1006/jmbi.1999.2721.

Nicotinic acetylcholine receptor at 4.6 A resolution: transverse tunnels in the channel wall

A Miyazawa  1 , Y Fujiyoshi, M Stowell, N Unwin
Affiliations

Nicotinic acetylcholine receptor at 4.6 A resolution: transverse tunnels in the channel wall

A Miyazawa et al. J Mol Biol. .

Abstract

The nicotinic acetylcholine (ACh) receptor is the neurotransmitter-gated ion channel responsible for the rapid propagation of electrical signals between cells at the nerve/muscle synapse. We report here the 4.6 A structure of this channel in the closed conformation, determined by electron microscopy of tubular crystals of Torpedo postsynaptic membranes embedded in amorphous ice. The analysis was conducted on images recorded at 4 K with a 300 kV field emission source, by combining data from four helical families of tubes (-16,6; -18,6; -15,7; -17,5), and applying three-dimensional corrections for lattice distortions. The study extends earlier work on the same specimen at 9 A resolution. Several features having functional implications now appear with better definition. The gate of the channel forms a narrow bridge, consisting of no more than one or two rings of side-chains, across the middle portion of the membrane-spanning pore. Tunnels, framed by twisted beta-sheet strands, are resolved in the extracellular wall of the channel connecting the water-filled vestibule to the putative ACh-binding pockets. A set of narrow openings through which ions can flow are resolved between alpha-helical segments forming part of the cytoplasmic wall of the channel. It is suggested that the extracellular tunnels are access routes to the binding pockets for ACh, and that the cytoplasmic openings serve as filters to exclude anions and other impermeant species from the vicinity of the pore. Both transverse pathways are likely to be important in achieving a rapid postsynaptic response.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

Publication types

LinkOut - more resources