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Evidence for Expression of Heteromeric Serotonin 5‐HT 3 Receptors in Rodents
Author(s) -
Hanna Michael C.,
Davies Paul A.,
Hales Tim G.,
Kirkness Ewen F.
Publication year - 2000
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.1471-4159.2000.0750240.x
Subject(s) - homomeric , receptor , biology , protein subunit , serotonin , microbiology and biotechnology , 5 ht receptor , cys loop receptors , 5 ht2 receptor , class c gpcr , biochemistry , agonist , acetylcholine receptor , gene , metabotropic receptor , nicotinic acetylcholine receptor
: The gene and cDNAs that encode a novel subunit of rodent serotonin 5‐HT 3 receptors were isolated from mouse and rat tissues. Each of the new rodent subunits shares 40% amino acid identity with the rat 5‐HT 3A subunit and 73% identity with the human 5‐HT 3B subunit. Despite a relatively low level of structural conservation, sequence analysis and functional studies suggest that the new rodent subunits are orthologues of the human 5‐HT 3B subunit. In common with homologous human receptors, rat heteromeric 5‐HT 3 receptors displayed a substantially larger single‐channel conductance than homomeric 5‐HT 3A receptors. In addition, the rat heteromeric receptors were less sensitive to antagonism by tubocurarine. However, in contrast to human heteromeric receptors, those of the rat displayed pronounced inward rectification of both the whole‐cell and single‐channel current amplitudes. Transcripts of the mouse 5‐HT 3A and 5‐HT 3B subunits are coexpressed in several cell lines that possess endogenous 5‐HT 3 receptors. In addition, treatment of rat PC12 cells with nerve growth factor induced expression of both subunit mRNAs, with a similar time course for accumulation of each transcript. The combination of functional data and expression patterns is consistent with the existence of heteromeric 5‐HT 3 receptors in rodent neurons.