Evidence for a Direct and Functional Interaction between the Regulators of G Protein Signaling-2 and Phosphorylated C Terminus of Cholecystokinin-2 Receptor

• Published in: Molecular pharmacology 2009-03, Vol.75 (3), p.502-513
• Main Authors: Langer, Ingrid, Tikhonova, Irina G., Boulègue, Cyril, Estève, Jean-Pierre, Vatinel, Sébastien, Ferrand, Audrey, Moroder, Luis, Robberecht, Patrick, Fourmy, Daniel
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Motifs - physiology; Amino Acid Sequence; Animals; Cercopithecus aethiops; COS Cells; Humans; Molecular Sequence Data; Peptide Fragments; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Peptide Fragments - physiology; Phosphorylation; Phosphorylation - physiology; Protein Binding; Protein Binding - physiology; Receptor, Cholecystokinin B; Receptor, Cholecystokinin B - chemistry; Receptor, Cholecystokinin B - metabolism; Receptor, Cholecystokinin B - physiology; RGS Proteins; RGS Proteins - chemistry; RGS Proteins - metabolism; RGS Proteins - physiology; Signal Transduction; Signal Transduction - physiology
• ISSN: 0026-895X; 1521-0111
• DOI: 10.1124/mol.108.051607

Signaling of G protein-coupled receptors (GPCRs) is regulated by different mechanisms. One of these involves regulators of G protein signaling (RGS), which are diverse and multifunctional proteins that bind to active Gα subunits of G proteins and act as GTPase-activating proteins. Little is known about the molecular mechanisms that govern the selective use of RGS proteins in living cells. We first demonstrated that CCK2R-mediated inositol phosphate production, known to be Gq-dependent, is more sensitive to RGS2 than to RGS4 and is insensitive to RGS8. Both basal and agonist-stimulated activities of the CCK2R are regulated by RGS2. By combining biochemical, functional, and in silico structural approaches, we demonstrate that a direct and functional interaction occurs between RGS2 and agonist-stimulated cholecystokinin receptor-2 (CCK2R) and identified the precise residues involved: phosphorylated Ser434 and Thr439 located in the C-terminal tail of CCK2R and Lys62, Lys63, and Gln67, located in the N-terminal domain of RGS2. These findings confirm previous reports that RGS proteins can interact with GPCRs to modulate their signaling and provide a molecular basis for RGS2 recognition by the CCK2R.