PeaTAR1B: Characterization of a second type 1 tyramine receptor of the American cockroach, Periplaneta americana. PeaTAR1B

The catecholamines norepinephrine and epinephrine regulate important physiological functions in vertebrates. In insects, these neuroactive substances are functionally replaced by the phenolamines octopamine and tyramine. Phenolamines activate specific guanine nucleotide-binding (G) protein-coupled receptors (GPCRs). Type 1 tyramine receptors are better activated by tyramine than by octopamine. In contrast, type 2 tyramine receptors are almost exclusively activated by tyramine. Functionally, activation of type 1 tyramine receptors leads to a decrease in intracellular concentration of cAMP ([cAMP]i) whereas type 2 tyramine receptors can mediate Ca2+ signals or both Ca2+ signals and effects on [cAMP]i. Here, we report that the American cockroach (Periplaneta americana) expresses a second type 1 tyramine receptor (PeaTAR1B).