title: A conserved motif for the transport of G protein-coupled receptors from the endoplasmic reticulum to the cell surface.
abstract: The structural determinants for the export trafficking of G protein-coupled receptors are poorly defined. In this report, we determined the role of carboxyl termini (CTs) of alpha2B-adrenergic receptor (AR) and angiotensin II type 1A receptor (AT1R) in their transport from the endoplasmic reticulum (ER) to the cell surface. The alpha2B-AR and AT1R mutants lacking the CTs were completely unable to transport to the cell surface and were trapped in the ER. Alanine-scanning mutagenesis revealed that residues Phe436 and Ile433-Leu444 in the CT were required for alpha2B-AR export. Insertion or deletion between Phe436 and Ile443-Leu444 as well as Ile443-Leu444 mutation to FF severely disrupted alpha2B-AR transport, indicating there is a defined spatial requirement, which is essential for their function as a single motif regulating receptor transport from the ER. Furthermore, the carboxyl-terminally truncated as well as Phe436 and Ile443-Leu444 mutants were unable to bind ligand and the alpha2B-AR CT conferred its transport properties to the AT1R mutant without the CT in a Phe436-Ile443-Leu444-dependent manner. These data suggest that the Phe436 and Ile443-Leu444 may be involved in both proper folding and export from the ER of the receptor. Similarly, residues Phe309 and Leu316-Leu317 in the CT were identified as essential for AT1R export. The sequence F(X)6LL (where X can be any residue, and L is leucine or isoleucine) is highly conserved in the membrane-proximal CTs of many G protein-coupled receptors and may function as a common motif mediating receptor transport from the ER to the cell surface.
authors.affiliation: Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Duvernay
authors.forename: Fuguo
authors.initials: F
authors.lastname: Zhou
authors.forename: Guangyu
authors.initials: G
authors.lastname: Wu
mesh_terms: D000409:Alanine / Q000737:chemistry; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007532:Isoleucine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D008024:Ligands; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010649:Phenylalanine / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000737:chemistry; D018341:Receptors, Adrenergic, alpha-2 / Q000737:chemistry; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D014162:Transfection
chemical_list: C547771:ADRA2B protein, human; D008024:Ligands; D044140:Receptor, Angiotensin, Type 1; D018341:Receptors, Adrenergic, alpha-2; D043562:Receptors, G-Protein-Coupled; D007532:Isoleucine; D010649:Phenylalanine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D007930:Leucine; D000409:Alanine