Sandbox 77: Difference between revisions

<scene name='71/716548/5-ht3_receptor/1'>The 5-HT3 receptor</scene> is a pentameric cation-selective ion channel and plays a role in neuronal excitation to release neurotransmitters from the postsynaptic neuron. Opening of the cation channel causes an influx of sodium and calcium through the receptor pore leading to a membrane depolarization. Five receptor subunits, A to E, have been found in humans but only subunits A and B have been found in rodents. When experimentally expressed in a host, the 5-HT3 receptor is comprised of either A or AB subunits which can result in a homopentameric receptor or a heteropentameric receptor respectively. The A and B subunits are found throughout the brain in areas such as the hippocampus and amygdala. 5-HT3 is a transmembrane channel that is stimulated to open state by the interaction of the receptor with serotonin in the extracellular space.<ref>Hassaine G,Cedric D, Luigino G, Romain W, Menno BT, Ruud H, Alexandra G, Henning S, Takashi T, Aline D, Christophe M, Xiao-Dan L, Frederic P, Horst V, Hugues N. ''X-ray Structure of the Mouse Serotonin 5-HT3 Receptor. Nature 512.7514 (2014): 276-81.[http://www.nature.com/nature/journal/v512/n7514/full/nature13552.html DOI:10.1038/nature13552]</ref> The binding site is comprised of six loops from two adjacent subunits in the extracellular N-terminal domain. Loops A, B and C form the principal subunit and contain the important side chains N128, W183 and Y234. Loops D, E and F form the complementary subunit of the binding site and contain the important side chains W90, Y143 and W195. The transmembrane region is comprised of multiple alpha helical structures and mediates ion flow and ion specificity.<ref> Thompson AJ, Lummis SCR. 5-HT3 Receptors. Curr Pharm Des. 2006; 12(28): 3615–3630. PMID:2664614 [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2664614/]</ref>