Functional expression of a locust tyramine receptor in murine erythroleukaemia cells.

The LCR/MEL system (Locus Control Region/Murine Erythroleukaemia cells) was employed to express and characterize the Locusta migratoria tyramine receptor (Tyr Loc), an insect G protein-coupled receptor. Functional agonist-dependent responses were recorded in stable, tyramine receptor expressing cell clones (MEL-Tyr Loc). Tyramine elicited a dose-dependent increase of cytosolic Ca[sup2+] -ions and an attenuation of forskolin-induced cyclic adenosine monophosphate (AMP) pro-duction. Octopamine was shown to be a weak agonist for both responses. In addition, yohimbine proved to be a potent tyramine receptor antagonist. This study reports the first application of the LCR / MEL expression system in functional assays for G protein-coupled receptors and therefore expands the capabilities of this system by exploiting the functionality of the signal transduction pathways. [ABSTRACT FROM AUTHOR]