The glycine receptor, or GlyR, is the receptor for the amino acid neurotransmitter glycine.

The glycine receptor is one of the most widely distributed inhibitory receptors in the central nervous system and has important roles in a variety of physiological processes, especially in mediating inhibitory neurotransmission in the spinal cord and brain stem.

Activation and inactivation: The receptor can be activated by a range of simple amino acids including glycine, β-alanine and taurine, and can be selectively blocked by the high-affinity competitive antagonist strychnine. Caffeine has recently been found also to be a competitive antagonist.

Arrangement of subunits: Strychnine-sensitive glycine receptors are members of a family of Ligand-gated ion channels. Receptors of this family are arranged as five subunits surrounding a central pore, with each subunit composed of four α helical transmembrane segments.

There are presently four known isoforms of the α-subunit (α1-4) of GlyR that are essential to bind ligands (GLRA1, GLRA2, GLRA3, GLRA4) and a single β-subunit (GLRB).

The adult form of the GlyR is the heteromeric α1β receptor, which is believed to have a stoichiometry (proportion) of three α1 subunits and two β subunits or four α1 subunits and one β subunit. The α-subunits are also able to form functional homo-pentameric receptors in heterologous expression systems in African clawed frog's oocytes or mammalian cell lines, and the α1 homomeric receptor is essential for studies of channel pharmacokinetics and pharmacodynamics.

Glycine receptors in diseases: Disruption of GlyR surface expression or reduced ability of expressed GlyRs to conduct chloride ions results in the rare neurological disorder, hyperekplexia. The disorder is characterized by an exaggerated response to unexpected stimuli which is followed by a temporary but complete muscular rigidity often resulting in an unprotected fall. Chronic injuries as a result of the falls are symptomatic of the disorder. A mutation in GLRA1 is responsible for some cases of stiff person syndrome.

Quantum dots have been used to track the diffusion of glycine receptors into the synapse of neurons.

Glycine (abbreviated as Gly or G) is an organic compound with the formula NH₂CH₂COOH. With only a hydrogen atom as its side chain, glycine is the smallest of the 20 amino acids commonly found in proteins.

Glycine receptor subunit alpha-1 is a protein that in humans is encoded by the GLRA1 gene.

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