Related Experiment Video
Updated: Jul 30, 2026

Assessing Two-dimensional Crystallization Trials of Small Membrane Proteins for Structural Biology Studies by Electron Crystallography
Published on: October 29, 2010
Expression, two-dimensional crystallization, and electron cryo-crystallography of recombinant gap junction membrane
V M Unger1, N M Kumar, N B Gilula
1Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Abstract:
We used electron cryo-microscopy and image analysis to examine frozen-hydrated, two-dimensional (2D) crystals of a recombinant, 30-kDa C-terminal truncation mutant of the cardiac gap junction channel formed by 43-kDa alpha(1) connexin. To our knowledge this is the first example of a structural analysis of a membrane protein that has been accomplished using microgram amounts of starting material. The recombinant alpha(1) connexin was expressed in a stably transfected line of baby hamster kidney cells and spontaneously assembled gap junction plaques. Detergent treatment with Tween 20 and 1,2-diheptanoyl-sn-phosphocholine resulted in well-ordered 2D crystals. A three-dimensional density (3D) map with an in-plane resolution of approximately 7.5 A revealed that each hexameric connexon was formed by 24 closely packed rods of density, consistent with an alpha-helical conformation for the four transmembrane domains of each connexin subunit. In the extracellular gap the aqueous channel was bounded by a continuous wall of protein that formed a tight electrical and chemical seal to exclude exchange of substances with the extracellular milieu.
More Related Videos
10:22Reconstitution of a Kv Channel into Lipid Membranes for Structural and Functional Studies
Published on: July 13, 2013
08:27Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy
Published on: January 7, 2019
Related Concept Videos
Gap Junctions
Non-gated Ion Channels
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Ligand-gated Ion Channels
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
Gap Junctions
Non-gated Ion Channels
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Ligand-gated Ion Channels
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...