Molecular cloning and pharmacological characterization of a Bombyx mori tyramine receptor selectively coupled to intracellular calcium mobilization

作者：Huang Jia; Ohta Hiroto; Inoue Noriko; Takao Haruka; Kita Tomo; Ozoe Fumiyo; Ozoe Yoshihisa^*

来源：Insect Biochemistry and Molecular Biology, 2009, 39(11): 842-849.

DOI：10.1016/j.ibmb.2009.10.001

• Bombyx mori
• Tyramine
• Octopamine
• G protein-coupled receptor
• Cloning
• Ca(2+)
• Agonist
• Antagonist

Tyramine (TA) is a biogenic amine in invertebrates. cDNA encoding the TA receptor (TAR) BmTAR2 was cloned from the nerve tissue of the silk-worm Bombyx mori. The receptor's functional and pharmacological properties were examined in BmTAR2-transfected HEK-293 cells. In [(3)H]TA binding assays, BmTAR2 showed considerably higher affinity for TA than for other biogenic amines, with an IC(50) value of 57.5 nM. Moreover, TA induced a dose-dependent increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in cells, with an EC(50) value of 11.6 nM, whereas octopamine and dopamine increased [Ca(2+)](i) only at concentrations above 100 mu M. A few antagonists were found to inhibit the TA-induced increases in [Ca(2+)](i) the rank order of potency was yohimbine > chlorpromazine > mianserin. TA showed no effect on intracellular CAMP concentration. The data indicate that BmTAR2 belongs to the second class of TARS, which are selectively coupled to intracellular Ca(2+) mobilization. RT-PCR analysis revealed that BmTAR2 was expressed predominantly in the nervous tissue of B. mori larvae, suggesting that TA has neurotransmitter and neuromodulatory roles that are mediated by BmTAR2.

• 出版日期2009-11