The C-terminal domain of the human EP4 receptor confers agonist-induced receptor desensitization in a receptor hybrid with the rat EP3beta receptor
Neuschäfer-Rube, F.; Hänecke, K.; Püschel, G.P.
Febs Letters 415(2): 119-124
ISSN/ISBN: 0014-5793 PMID: 9350980 Accession: 009530132
Prostaglandin E-2 receptors (EPR), which belong to the family of heterotrimeric G protein-coupled ectoreceptors with seven transmembrane domains, can be classified into four subtypes according to their ligand binding and G protein coupling specificity. Of these, EP-3beta-R is coupled to G-i, whereas EP-4R is coupled to G-s. EP-4R, in contrast to EP-3beta-R, shows agonist-induced desensitization. The C-terminal domain and the third intracellular loop of these receptors have been implicated in G protein coupling specificity and desensitization. Here, receptor hybrids consisting of the main portion of rat EP-3beta-R and either the C-terminal domain or the third intracellular loop of human EP-4R were used to study the contribution of the respective receptor domains to G protein coupling and desensitization. Neither the EP-4R C-terminal domain nor the EP-4R third intracellular loop alone was sufficient to change the coupling specificity of the rEP-3hEP-4 receptor hybrids from G-i to G-s or to confer additional G-s coupling. However, the EP-4R C-terminal domain but not the third intracellular loop was necessary and sufficient to mediate rapid agonist-induced, second messenger independent desensitization in the G-i-coupled hybrid receptors.