Gamma-aminobutyric acid type A receptor picrotoxin binding site (GABA-A receptor picrotoxin site)

The picrotoxin/TBPS binding site is a critical allosteric site located within the chloride ion channel pore of the gamma-aminobutyric acid type A (GABA-A) receptor (Olsen, 2006). This site is distinct from the GABA and benzodiazepine binding sites and is primarily targeted by non-competitive antagonists that block the flow of chloride ions (Sigel & Steinmann, 2012). By obstructing the channel, these ligands prevent neuronal hyperpolarization, leading to increased CNS excitability and potentially life-threatening seizures (StatPearls, 2023). Historically, this site has been used to study the mechanism of convulsant drugs like pentylenetetrazol and various insecticides, including lindane and fipronil (PubChem, 2024). While it is not a common target for therapeutic drug development due to the high risk of toxicity, it remains a major focus in toxicology and neuropharmacology research (NIH, 2023). The site's structure is formed by the M2 transmembrane helices of the receptor subunits, making it a conserved feature across different GABA-A receptor isoforms (UniProt, 2024).

Other names

Picrotoxin binding siteTBPS binding siteConvulsant binding siteGABA-A receptor chloride channel poreNon-competitive GABA antagonist site

Non-competitive antagonism via pore blockade of the chloride ion channel, preventing chloride influx and reducing inhibitory postsynaptic potentials.