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Immunological Characterization and Transmembrane Topology of 5‐Hydroxytryptamine 3 Receptors by Functional Epitope Tagging
Author(s) -
Mukerji Jishnu,
Haghighi Ali,
Séguéla Philippe
Publication year - 1996
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1996.66031027.x
Subject(s) - homomeric , class c gpcr , biology , ligand gated ion channel , transmembrane domain , receptor , microbiology and biotechnology , ion channel , neurotransmitter receptor , epitope , heterologous expression , acetylcholine receptor , biochemistry , protein subunit , glutamate receptor , metabotropic receptor , genetics , gene , antibody , recombinant dna
5‐Hydroxytryptamine 3 (5‐HT 3 ) receptors are the only known monoamine receptors mediating fast excitatory responses in mammalian neurons. Their primary structure as well as their electrophysiological and pharmacological properties show a phylogenetic relation to nicotinic acetylcholine, GABA A , and glycine receptors. As a prototypical member of this gene superfamily, we investigated the membrane topology of functional homomeric 5‐HT 3 receptors by using epitope tagging of the channel subunits expressed in heterologous systems. Visualization of 5‐HT 3 receptors in transfected COS‐7 cells, either in western blot (molecular mass 61.2 ± 0.8 kDa) or in situ, was performed with previously characterized antibodies recognizing artificial epitopes as well as with anti‐fusion protein antibodies directed against a wild‐type receptor intracellular domain. The extracellular location of the distal C‐terminal tagged domain demonstrates the presence of a fourth transmembrane domain in 5‐HT 3 serotonin‐gated channels. In this region, the significant homology between members of this class of neurotransmitter‐gated channels suggests strongly that they have a common transmembrane organization basically different from glutamate‐gated and ATP‐gated channels.