Glycine receptors (GlyRs) mediate ionotropic inhibitory neurotransmission in the CNS where they play an essential role in inhibition of motor neurons in the spinal cord and brainstem¹. The glycine receptor is composed of three ligand-binding subunits of 48 kDa (α) and two homologous polypeptides of 58 kDa (β) that span the postsynaptic membrane in a pentameric arrangement to form a Cl^--selective channel². So far, at least three different α-subunit variants of the GlyR have been identified: α1, α2 and α3³. Homo-oligomeric α2 receptors have a low strychnine-binding affinity and are considered to represent a neonatal form of GlyR, which is replaced during development by receptors containing the α1 subunit. Adult GlyRs are predominantly composed of α1 and β subunits, the α3 subunit being expressed at low levels in only a few brain regions⁴.

GlyRα1 subunits are widely expressed and contribute to many processes in the CNS, including inflammatory pain perception, modulation of auditory and visual pathways, and neurotransmission in the cerebellar cortex⁵.

Mutations in glycine receptor α1 subunits cause human hereditary hyperekplexia, a disorder characterized by an exaggerated startle response, which is a consequence of the role of GlyRs in motor reflex circuits of the spinal cord⁶.