Glycine receptor alpha 1
The GLRA1 gene provides instructions for making one part, the alpha (α)1 subunit, of the glycine receptor protein. The glycine receptor is embedded in the membrane of nerve cells (neurons) in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem). The glycine receptor is made up of five subunits: two α1 subunits and three beta (β) subunits. The β subunit is produced from a different gene.
Receptor proteins have specific sites into which certain other molecules, called ligands, fit like keys into locks. Together, ligands and their receptors trigger signals that affect cell development and function. The ligand for the glycine receptor is the protein building block (amino acid) glycine. This molecule also acts as a neurotransmitter, which is a chemical messenger that transmits signals in the nervous system.
When glycine attaches (binds) to the glycine receptor, the receptor opens to allow negatively charged chlorine atoms (chloride ions) to enter the neuron. This influx of chloride ions reduces the neurons's ability to transmit signals to other neurons. Because they stop (inhibit) signaling, glycine receptors are known as inhibitory receptors.
2. Health Conditions Related to Genetic Changes
2.1. Hereditary hyperekplexia
More than 60 mutations in the GLRA1 gene have been found to cause hereditary hyperekplexia. This condition is most often seen in infants who experience increased muscle tone (hypertonia) and an exaggerated startle reaction to unexpected stimuli, especially loud noises. The startle reaction can trigger a brief period of rigidity and immobility, and in some cases, infants stop breathing. Most GLRA1 gene mutations change single amino acids in the α1 subunit of the glycine receptor protein. The most common mutation replaces the amino acid arginine with the amino acid leucine at protein position 271 (written as Arg271Leu or R271L).
GLRA1 gene mutations that cause hereditary hyperekplexia impair the ability of the glycine receptor protein to respond to the ligand glycine. Some GLRA1 gene mutations alter the structure of the glycine receptor, which can prevent the receptor from opening or cause it to open without the presence of glycine. Other mutations prevent the receptor from reaching the cell membrane. When the glycine receptor is dysfunctional or missing, chloride ions enter the cell when they are not needed or cannot enter the cell at all. The resulting increase in cell signaling in the spinal cord and brainstem likely causes the abnormal muscle movements, exaggerated startle reaction, and other signs and symptoms of hereditary hyperekplexia.
3. Other Names for This Gene
glycine receptor, alpha 1
glycine receptor, alpha 1 isoform 1 precursor
glycine receptor, alpha 1 isoform 2 precursor
The entry is from https://medlineplus.gov/genetics/gene/glra1
- Balint B, Thomas R. Hereditary Hyperekplexia Overview. 2007 Jul 31 [updated2019 Dec 19]. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University ofWashington, Seattle; 1993-2020. Available fromhttp://www.ncbi.nlm.nih.gov/books/NBK1260/
- Bode A, Wood SE, Mullins JG, Keramidas A, Cushion TD, Thomas RH, Pickrell WO, Drew CJ, Masri A, Jones EA, Vassallo G, Born AP, Alehan F, Aharoni S, Bannasch G,Bartsch M, Kara B, Krause A, Karam EG, Matta S, Jain V, Mandel H, Freilinger M,Graham GE, Hobson E, Chatfield S, Vincent-Delorme C, Rahme JE, Afawi Z, Berkovic SF, Howell OW, Vanbellinghen JF, Rees MI, Chung SK, Lynch JW. New hyperekplexiamutations provide insight into glycine receptor assembly, trafficking, andactivation mechanisms. J Biol Chem. 2013 Nov 22;288(47):33745-59. doi:10.1074/jbc.M113.509240.
- Harvey RJ, Topf M, Harvey K, Rees MI. The genetics of hyperekplexia: more thanstartle! Trends Genet. 2008 Sep;24(9):439-47. doi: 10.1016/j.tig.2008.06.005.
- Masri A, Chung SK, Rees MI. Hyperekplexia: Report on phenotype and genotype of16 Jordanian patients. Brain Dev. 2017 Apr;39(4):306-311. doi:10.1016/j.braindev.2016.10.010.
- Villmann C, Oertel J, Melzer N, Becker CM. Recessive hyperekplexia mutationsof the glycine receptor alpha1 subunit affect cell surface integration andstability. J Neurochem. 2009 Nov;111(3):837-47. doi:10.1111/j.1471-4159.2009.06372.x.
- Zhang Y, Bode A, Nguyen B, Keramidas A, Lynch JW. Investigating the Mechanism by Which Gain-of-function Mutations to the α1 Glycine Receptor CauseHyperekplexia. J Biol Chem. 2016 Jul 15;291(29):15332-41. doi:10.1074/jbc.M116.728592.