Glycine receptor

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Glycine receptor
Secondary to quaternary structure 2α3β
Identifier
Gene name (s) GLRA1 , GLRA2 , GLRA3 , GLRA4 , GLRB
Transporter classification
TCDB 1.A.9.3.1
designation Ligand-gated ion channels (Cys-Loop)
Occurrence
Parent taxon Bilateral animals

The glycine receptor (GlyR) is a protein complex in the cell membrane of bilateral animals , which occurs mainly in nerve cells , but also in sperm and macrophages . GlyRs makes the membrane permeable to chloride - ions when a molecule glycine binds to GlyRs. It is therefore an ion channel controlled by glycine .

GlyR is made up of five protein subunits (2α3β), with four possible α units being interchangeable. Mutations at Glra1 - and on GLRB - gene are responsible for familial Hyperekplexia (sthe).

Like the GABA A receptor and the nicotinic acetylcholine receptor ( nAChR ), GlyR belongs to the class of ligand-controlled ion channels (ionotropic receptor).

function

GlyR is localized on the postsynaptic cell membrane of neurons and, when activated by glycine, leads to a reduction in cell excitability. The inhibition of excitation occurs through an influx of chloride ions into the cell, induced during ligand binding. Depending on the concentration gradient of chloride ions between the extra and intracellular space, the membrane potential changes to different degrees. It will be more negative in any case. A hyperpolarization takes place, which then inhibits the downstream cell (inhibitory postsynaptic potential).

construction

As with GABA (A) R and nAChR, the functional GlyR consists of five subunits (pentamer) that are grouped together to form a transmembrane protein with a central pore region. There are two subunits (alpha, beta) of GlyR that can be distinguished in terms of their amino acid sequence and size, each alpha subunit having the binding site for the neurotransmitter and the beta subunit assuming a structural function. 2 alpha assemble natively with 3 beta subunits to form the pentameric receptor. However, 5 alpha subunits can also form a functional receptor on their own. The alpha subunits can be further subdivided into 4 variants (alpha1 to alpha4), the occurrence of which depends on the region in the CNS and the stage of development of the organism. When the GlyR is organized at the postsynapse, it binds to an intracellularly localized protein (gepherin), which couples the receptor to the cytoskeleton.

Receptor modulators

The plant toxin strychnine and the exotoxin tetanospasmin act on the glycine receptor. As the inhibiting effect ceases, both substances cause spastic paralysis .

See also

Individual evidence

  1. ^ A b Joseph W. Lynch / IUPHAR: Glycine receptors, introductory chapter. , Accessed on 29/03/2012
  2. ↑ UniProt P23415 , UniProt P48167
  3. ↑ Kang HC, Jeong You S, Jae Chey M, Sam Baik J, Kim JW, Ki CS: Identification of a de novo Lys304Gln mutation in the glycine receptor alpha-1 subunit gene in a Korean infant with hyperekplexia . In: Mov. Disord. . 23, No. 4, March 2008, pp. 610-3. doi : 10.1002 / mds.21909 . PMID 18175347 .
  4. ↑ Sirén A, Legros B, Chahine L, Misson JP, Pandolfo M: Hyperekplexia in Kurdish families: a possible GLRA1 founder mutation . In: Neurology . 67, No. 1, July 2006, pp. 137-9. doi : 10.1212 / 01.wnl.0000223347.73493.af . PMID 16832093 .
  5. ↑ Alberto J. Espay, José Biller: Concise Neurology . Lippincott Williams & Wilkins, 2011, ISBN 978-1-4511-1360-0 , pp. 134-.
  6. ↑ GK Bergey, RL MacDonald, WH Habig, MC Hardegree, PG Nelson: Tetanus toxin: convulsant action on mouse spinal cord neurons in culture. In: The Journal of neuroscience: the official journal of the Society for Neuroscience. Volume 3, Number 11, November 1983, pp. 2310-223, PMID 6631482 .