Characterization of the subunit composition and structure of native adult glycine receptors

The strychnine-sensitive pentameric Glycine Receptor (GlyR) mediates fast inhibitory neurotransmission in the mammalian nervous system. Only heteromeric GlyRs mediate synaptic transmission, since they contain the {beta} subunit that permits clustering at the synapse through its interaction with scaffolding proteins. Here we show that 2 and {beta} subunits assemble with an unexpected 4:1 stoichiometry to produce GlyR with native electrophysiological properties. We determined structures in multiple functional states at 3.6 - 3.8 [A] resolutions and show 2{beta} GlyR assembly mechanism. Furthermore, we show that one single {beta} subunit in each GlyR gives rise to the characteristic electrophysiological properties of heteromeric GlyR, while more {beta} subunits renders GlyR non-conductive. A single {beta} subunit ensures a univalent GlyR-scaffold linkage, which means the scaffold alone regulates the cluster properties.