Stoichiometry and Subunit Arrangement of α1β Glycine Receptors As Determined by Atomic Force Microscopy

The glycine receptor is an anion-permeable member of the Cys-loop ion channel receptor family. Synaptic glycine receptors predominantly comprise pentameric alpha 1 beta subunit heteromers. To date, attempts to define the subunit stoichiometry and arrangement of these receptors have not yielded consistent results. Here we introduced FLAG and six-His epitopes into alpha 1 and beta subunits, respectively, and imaged single antibody-bound alpha 1 beta receptors using atomic force microscopy. This permitted us to infer the number and relative locations of the respective subunits in functional pentamers. Our results indicate an invariant 2 alpha 1:3 beta stoichiometry with a beta-alpha-beta-alpha-beta subunit arrangement.