The GLRA1 gene encodes the alpha-1 subunit of the glycine receptor protein. The pentameric glycine receptor is made up of two alpha-1 subunits and three beta subunits. It functions as a ligand-gated chloride channel in neurons and is activated by binding to extracellular glycine. By allowing chloride ions into the cell, the receptor is responsible for postsynaptic inhibition and it plays an important role in the down-regulation of neuronal excitability. Channel activity is also potentiated by zinc, ethanol and taurine.
Defects in the GLRA1 gene result in a non-functioning glycine receptor that does not allow chloride ions to enter the cells. This leads to increased cell signaling and neuronal excitability such as the exaggerated startle reaction and muscle contractions seen in Hyperekplexia, Hereditary 1 disorder (HKPX1).