title: Characterization of a tyramine receptor from Caenorhabditis elegans.
abstract: Octopamine (OA) plays an important role in the regulation of a number of key processes in nematodes, including pharyngeal pumping, locomotion and egg-laying. However, while putative OA receptors can be tentatively identified in the Caenorhabditis elegans database, no OA receptors have been functionally characterized from any nematode. We have isolated two cDNAs, ser-2 and ser-2a, encoding putative C.elegans serotonin/OA receptors (C02D4.2, ser-2). The sequences of these cDNAs differ from that predicted by GeneFinder and lack 42 bp of exon 2. In addition, ser-2a appears to be alternatively spliced and lacks a predicted 23 amino acids in the third intracellular loop. COS-7 cells expressing SER-2 bind [3H]LSD in the low nM range and exhibit Kis for tyramine, octopamine and serotonin of 0.07, 2, and 13.7 micro m, respectively. Significantly, tyramine reduces forskolin-stimulated cAMP levels in HEK293 cells stably expressing SER-2 with an IC50 of about 360 nm, suggesting that SER-2 is a tyramine receptor.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive / Q000502:physiology; D019556:COS Cells; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008024:Ligands; D008969:Molecular Sequence Data; D009655:Octopamine / Q000378:metabolism; D010802:Phylogeny; D017982:Receptors, Biogenic Amine / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012701:Serotonin / Q000378:metabolism; D014439:Tyramine / Q000378:metabolism / Q000494:pharmacology
chemical_list: D029742:Caenorhabditis elegans Proteins; D018076:DNA, Complementary; D008024:Ligands; D017982:Receptors, Biogenic Amine; C027604:norsynephrine receptor; C066175:tyramine receptor; D009655:Octopamine; D005576:Colforsin; D012701:Serotonin; D000242:Cyclic AMP; D014439:Tyramine