A Polyaromatic Caveolin-Binding-Like Motif in the Cytoplasmic Tail of the Type 1 Receptor for Angiotensin II Plays an Important Role in Receptor Trafficking and Signaling

• Published in: Endocrinology (Philadelphia) 2002-12, Vol.143 (12), p.4702-4710
• Main Authors: Leclerc, Patrice C, Auger-Messier, Mannix, Lanctot, Pascal M, Escher, Emanuel, Leduc, Richard, Guillemette, Gaétan
• Format: Article
• Language: English
• Subjects: Agonists; Alanine; Angiotensin AT1 receptors; Angiotensin II; Angiotensin II - metabolism; Animals; Binding; Binding Sites; Caveolae; Caveolin; Caveolin 1; Caveolins - metabolism; Cell Membrane - chemistry; Cell Membrane - metabolism; COS Cells; Dopamine; Dopamine D1 receptors; Fetal Proteins; Gene Expression; Green Fluorescent Proteins; Humans; Inositol; Inositol phosphates; Inositol Phosphates - metabolism; Inositols; Internalization; Iodine Radioisotopes; Kinetics; Localization; Luminescent Proteins; Membrane Proteins - pharmacology; Membranes; Microscopy, Confocal; Molecular Chaperones; Mutagenesis; Protein transport; Proteins; Receptor, Angiotensin, Type 1; Receptors; Receptors, Angiotensin - chemistry; Receptors, Angiotensin - genetics; Receptors, Angiotensin - physiology; Receptors, Dopamine D1 - genetics; Recombinant Fusion Proteins; Regulatory proteins; Residues; Signal Transduction; Structure-Activity Relationship; Transfection
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/en.2002-220679

The type 1 receptor for angiotensin II (AT1) is a member of the G protein-coupled receptor family. The presence of a caveolin-binding-like motif (φXφXXXXφXXφ where φ is an aromatic residue) within the cytoplasmic tail of the AT1 receptor suggests an implication for caveolae in the functionality of this receptor. We constructed a mutant AT1 receptor where each of the aromatic residues in the caveolin-binding-like motif were replaced by alanine (AT1-YFFY/A). Mutation of this motif considerably reduced the plasma membrane expression of the receptor that accumulated in a perinuclear compartment. The agonist-induced internalization rate of the AT1-YFFY/A receptor was also significantly reduced. Finally, the AT1-YFFY/A receptor was poorly activated as indicated by a low agonist-induced production of inositol phosphates. Unexpectedly, the proportion of AT1 receptor found in caveolae was minor under basal conditions and did not increase under stimulated conditions. Coexpression of the AT1 receptor with dopamine receptor interacting protein of 78 kDa, a protein implicated in the cellular routing of the dopamine D1 receptor, increased plasma membrane expression of the AT1 receptor. However, dopamine receptor interacting protein of 78 kDa had no effect on the expression of the AT1-YFFY/A receptor. Taken together, these results suggest that the caveolin-binding-like motif of the AT1 receptor does not promote localization of the receptor to caveolae but rather may act as a docking site for regulatory proteins modulating the routing and the functionality of the receptor.