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SER‐7b, a constitutively active Gα s coupled 5‐HT 7 ‐like receptor expressed in the Caenorhabditis elegans M4 pharyngeal motorneuron
Author(s) -
Hobson Robert J.,
Geng Jinming,
Gray Anjali D.,
Komuniecki Richard W.
Publication year - 2003
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.1471-4159.2003.01967.x
Subject(s) - caenorhabditis elegans , serotonin , tryptamine , biology , receptor , 5 ht receptor , microbiology and biotechnology , mutant , biogenic amine , complementary dna , gene , biochemistry
Serotonin plays a key role in the regulation of pharyngeal pumping in nematodes. We have isolated a Caenorhabditis elegans cDNA (C09B7.1b, ser‐7b ) with greatest identity to the 5‐HT 7 receptor family. Membranes from COS‐7 cells expressing SER‐7b exhibit saturable [ 3 H]‐LSD binding ( K d = 45 n m ) that is inhibited by serotonin (5‐HT) and tryptamine, but not by other physiological biogenic amines. Expression of SER‐7b in COS‐7 cells results in dramatic increase in basal cAMP levels over untransfected cells that is dependent on expression level. 5‐HT further elevates cAMP levels in a dose‐dependent manner (pEC 50 = 7.5 ± 0.5). Mammalian 5‐HT 7 receptor inverse agonists reduce constitutive activity, with methiothepin the most potent (pIC 50 = 7.8 ± 0.1). Ser‐7 ::GFP transcriptional fusions reveal that SER‐7b appears to be expressed solely in the M4 pharyngeal motorneuron after hatching. This is the first report of a Gα s coupled biogenic amine receptor in nematodes and the localization of SER‐7b in the M4 pharyngeal motorneuron suggests that SER‐7b may play a role in the regulation of pharyngeal pumping.