Biased signaling favoring Gi over β-arrestin promoted by an apelin fragment lacking the C-terminal phenylalanine

Journal of Biological Chemistry

Volumn 289, Issue 35, 2014, Pages 24599-24610

  Ceraudo, Emilie ^a,b,c   Galanth, Cécile ^a,b,c   Carpentier, Eric ^d   Banegas Font, Inmaculada ^a,b,c   Schonegge, Anne Marie ^d   Alvear Perez, Rodrigo ^a,b,c   Iturrioz, Xavier ^a,b,c   Bouvier, Michel ^d   Llorens Cortes, Catherine ^a,b,c  

^a INSERM   (France)

^b PSL RESEARCH UNIVERSITY   (France)

^c CNRS   (France)

^d INSTITUTE FOR RESEARCH IN IMMUNOLOGY AND CANCER   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

AMINO ACIDS; BLOOD PRESSURE;

ARRESTINS; SIGNALING PATHWAYS; STRUCTURAL BASIS;

CHEMICAL ACTIVATION;

APELIN; APELIN RECEPTOR; BETA ARRESTIN; CYCLIC AMP; INHIBITORY GUANINE NUCLEOTIDE BINDING PROTEIN; MITOGEN ACTIVATED PROTEIN KINASE 1; MITOGEN ACTIVATED PROTEIN KINASE 3; PHENYLALANINE; APLN PROTEIN, RAT; PRIMER DNA; RETINA S ANTIGEN; SIGNAL PEPTIDE;

ANIMAL TISSUE; ARTICLE; BINDING AFFINITY; BIOSENSOR; BLOOD PRESSURE REGULATION; CARBOXY TERMINAL SEQUENCE; CONTROLLED STUDY; ENZYME ACTIVATION; ENZYME ACTIVITY; ENZYME PHOSPHORYLATION; ENZYME STRUCTURE; HUMAN; HUMAN CELL; INTERNALIZATION; MALE; NONHUMAN; PRIORITY JOURNAL; PROTEIN INDUCTION; PROTEIN PROTEIN INTERACTION; RAT; SIGNAL TRANSDUCTION; ANIMAL; HEK293 CELL LINE; METABOLISM; NUCLEOTIDE SEQUENCE; PHOSPHORYLATION; POLYMERASE CHAIN REACTION; SPRAGUE DAWLEY RAT;

ANIMALS; ARRESTINS; BASE SEQUENCE; DNA PRIMERS; ENZYME ACTIVATION; GTP-BINDING PROTEIN ALPHA SUBUNITS, GI-GO; HEK293 CELLS; HUMANS; INTERCELLULAR SIGNALING PEPTIDES AND PROTEINS; MALE; MAP KINASE SIGNALING SYSTEM; PHENYLALANINE; PHOSPHORYLATION; POLYMERASE CHAIN REACTION; RATS; RATS, SPRAGUE-DAWLEY; SIGNAL TRANSDUCTION;

EID: 84906861756     PISSN: 00219258     EISSN: 1083351X     Source Type: Journal    
DOI: 10.1074/jbc.M113.541698     Document Type: Article

References (65)

1. Tatemoto, K., Hosoya, M., Habata, Y., Fujii, R., Kakegawa, T., Zou, M. X., Kawamata, Y., Fukusumi, S., Hinuma, S., Kitada, C., Kurokawa, T., Onda, H., and Fujino, M. (1998) Isolation and characterization of a novel endogenous peptide ligand for the human APJ receptor. Biochem. Biophys. Res. Commun. 251, 471-476 (Pubitemid 28505047)
2. O'Dowd, B. F., Heiber, M., Chan, A., Heng, H. H., Tsui, L. C., Kennedy, J. L., Shi, X., Petronis, A., George, S. R., and Nguyen, T. (1993) A human gene that shows identity with the gene encoding the angiotensin receptor is located on chromosome 11. Gene 136, 355-360 (Pubitemid 24049270)
3. Devic, E., Rizzoti, K., Bodin, S., Knibiehler, B., and Audigier, Y. (1999) Amino acid sequence and embryonic expression of msr/apj, the mouse homolog of Xenopus X-msr and human APJ. Mech. Dev. 84, 199-203 (Pubitemid 29331675)
4. De Mota, N., Lenkei, Z., and Llorens-Cortès, C. (2000) Cloning, pharmacological characterization and brain distribution of the rat apelin receptor. Neuroendocrinology 72, 400-407 (Pubitemid 32037653)
5. O'Carroll, A. M., Selby, T. L., Palkovits, M., and Lolait, S. J. (2000) Distribution of mRNA encoding B78/apj, the rat homologue of the human APJ receptor, and its endogenous ligand apelin in brain and peripheral tissues. Biochim. Biophys. Acta 1492, 72-80 (Pubitemid 30349182)
6. Habata, Y., Fujii, R., Hosoya, M., Fukusumi, S., Kawamata, Y., Hinuma, S., Kitada, C., Nishizawa, N., Murosaki, S., Kurokawa, T., Onda, H., Tatemoto, K., and Fujino, M. (1999) Apelin, the natural ligand of the orphan receptor APJ, is abundantly secreted in the colostrum. Biochim. Biophys. Acta 1452, 25-35 (Pubitemid 29486739)
7. Lee, D. K., Cheng, R., Nguyen, T., Fan, T., Kariyawasam, A. P., Liu, Y., Osmond, D. H., George, S. R., and O'Dowd, B. F. (2000) Characterization of apelin, the ligand for the APJ receptor. J. Neurochem. 74, 34-41 (Pubitemid 30012752)
8. Azizi, M., Iturrioz, X., Blanchard, A., Peyrard, S., De Mota, N., Chartrel, N., Vaudry, H., Corvol, P., and Llorens-Cortes, C. (2008) Reciprocal regulation of plasma apelin and vasopressin by osmotic stimuli. J. Am. Soc. Nephrol. 19, 1015-1024
9. De Mota, N., Reaux-Le Goazigo, A., El Messari, S., Chartrel, N., Roesch, D., Dujardin, C., Kordon, C., Vaudry, H., Moos, F., and Llorens-Cortes, C. (2004) Apelin, a potent diuretic neuropeptide counteracting vasopressin actions through inhibition of vasopressin neuron activity and vasopressin release. Proc. Natl. Acad. Sci. U.S.A. 101, 10464-10469 (Pubitemid 38924948)
10. Iturrioz, X., Alvear-Perez, R., De Mota, N., Franchet, C., Guillier, F., Leroux, V., Dabire, H., Le Jouan, M., Chabane, H., Gerbier, R., Bonnet, D., Berdeaux, A., Maigret, B., Galzi, J. L., Hibert, M., and Llorens-Cortes, C. (2010) Identification and pharmacological properties of E339-3D6, the first nonpeptidic apelin receptor agonist. FASEB J. 24, 1506-1517
11. Medhurst, A. D., Jennings, C. A., Robbins, M. J., Davis, R. P., Ellis, C., Winborn, K. Y., Lawrie, K. W., Hervieu, G., Riley, G., Bolaky, J. E., Herrity, N. C., Murdock, P., and Darker, J. G. (2003) Pharmacological and immunohistochemical characterization of the APJ receptor and its endogenous ligand apelin. J. Neurochem. 84, 1162-1172 (Pubitemid 36330668)
12. Zhou, N., Fan, X., Mukhtar, M., Fang, J., Patel, C. A., DuBois, G. C., and Pomerantz, R. J. (2003) Cell-cell fusion and internalization of the CNS-based, HIV-1 co-receptor, APJ. Virology 307, 22-36 (Pubitemid 36349433)
13. Masri, B., Morin, N., Cornu, M., Knibiehler, B., and Audigier, Y. (2004) Apelin (65-77) activates p70 S6 kinase and is mitogenic for umbilical endothelial cells. FASEB J. 18, 1909-1911 (Pubitemid 39602280)
14. El Messari, S., Iturrioz, X., Fassot, C., De Mota, N., Roesch, D., and Llorens-Cortes, C. (2004) Functional dissociation of apelin receptor signaling and endocytosis: implications for the effects of apelin on arterial blood pressure. J. Neurochem. 90, 1290-1301 (Pubitemid 39223633)
15. Evans, N. A., Groarke, D. A., Warrack, J., Greenwood, C. J., Dodgson, K., Milligan, G., and Wilson, S. (2001) Visualizing differences in ligand-induced β-arrestin-GFP interactions and trafficking between three recently characterized G protein-coupled receptors. J. Neurochem. 77, 476-485 (Pubitemid 32298742)
16. Reaux, A., De Mota, N., Skultetyova, I., Lenkei, Z., El Messari, S., Gallatz, K., Corvol, P., Palkovits, M., and Llorens-Cortès, C. (2001) Physiological role of a novel neuropeptide, apelin, and its receptor in the rat brain. J. Neurochem. 77, 1085-1096 (Pubitemid 32467063)
17. Brailoiu, G. C., Dun, S. L., Yang, J., Ohsawa, M., Chang, J. K., and Dun, N. J. (2002) Apelin-immunoreactivity in the rat hypothalamus and pituitary. Neurosci. Lett. 327, 193-197
18. O'Carroll, A. M., Don, A. L., and Lolait, S. J. (2003) APJ receptor mRNA expression in the rat hypothalamic paraventricular nucleus: regulation by stress and glucocorticoids. J. Neuroendocrinol. 15, 1095-1101 (Pubitemid 37369171)
19. Reaux-Le Goazigo, A., Morinville, A., Burlet, A., Llorens-Cortes, C., and Beaudet, A. (2004) Dehydration-induced cross-regulation of apelin and vasopressin immunoreactivity levels in magnocellular hypothalamic neurons. Endocrinology 145, 4392-4400 (Pubitemid 39120589)
20. Blanchard, A., Steichen, O., De Mota, N., Curis, E., Gauci, C., Frank, M., Wuerzner, G., Kamenicky, P., Passeron, A., Azizi, M., and Llorens-Cortes, C. (2013) An abnormal apelin/vasopressin balance may contribute to water retention in patients with the syndrome of inappropriate antidiuretic hormone (SIADH) and heart failure. J. Clin. Endocrinol. Metab. 98, 2084-2089
21. Japp, A. G., Cruden, N. L., Amer, D. A., Li, V. K., Goudie, E. B., Johnston, N. R., Sharma, S., Neilson, I., Webb, D. J., Megson, I. L., Flapan, A. D., and Newby, D. E. (2008) Vascular effects of apelin in vivo in man. J. Am. Coll. Cardiol. 52, 908-913
22. Ashley, E. A., Powers, J., Chen, M., Kundu, R., Finsterbach, T., Caffarelli, A., Deng, A., Eichhorn, J., Mahajan, R., Agrawal, R., Greve, J., Robbins, R., Patterson, A. J., Bernstein, D., and Quertermous, T. (2005) The endogenous peptide apelin potently improves cardiac contractility and reduces cardiac loading in vivo. Cardiovasc. Res. 65, 73-82 (Pubitemid 40038480)
23. Berry, M. F., Pirolli, T. J., Jayasankar, V., Burdick, J., Morine, K. J., Gardner, T. J., and Woo, Y. J. (2004) Apelin has in vivo inotropic effects on normal and failing hearts. Circulation 110, II187-II193 (Pubitemid 39263721)
24. Szokodi, I., Tavi, P., Földes, G., Voutilainen-Myllylä, S., Ilves, M., Tokola, H., Pikkarainen, S., Piuhola, J., Rysä, J., Tóth, M., and Ruskoaho, H. (2002)Apelin, the novel endogenous ligand of the orphan receptor APJ, regulates cardiac contractility. Circ. Res. 91, 434-440 (Pubitemid 35034212)
25. Kuba, K., Zhang, L., Imai, Y., Arab, S., Chen, M., Maekawa, Y., Leschnik, M., Leibbrandt, A., Makovic, M., Schwaighofer, J., Beetz, N., Musialek, R., Neely, G. G., Komnenovic, V., Kolm, U., Metzler, B., Ricci, R., Hara, H., Meixner, A., Nghiem, M., Chen, X., Dawood, F., Wong, K. M., Sarao, R., Cukerman, E., Kimura, A., Hein, L., Thalhammer, J., Liu, P. P., and Penninger, J. M. (2007) Impaired heart contractility in Apelin gene-deficient mice associated with aging and pressure overload. Circ. Res. 101, e32-e42 (Pubitemid 47267711)
26. Tatemoto, K., Takayama, K., Zou, M. X., Kumaki, I., Zhang, W., Kumano, K., and Fujimiya, M. (2001) The novel peptide apelin lowers blood pressure via a nitric oxide-dependent mechanism. Regul. Pept. 99, 87-92 (Pubitemid 32522535)
27. Lee, D. K., Saldivia, V. R., Nguyen, T., Cheng, R., George, S. R., and O'Dowd, B. F. (2005) Modification of the terminal residue of apelin-13 antagonizes its hypotensive action. Endocrinology 146, 231-236 (Pubitemid 40051744)
28. Iturrioz, X., Gerbier, R., Leroux, V., Alvear-Perez, R., Maigret, B., and Llorens-Cortes, C. (2010) By interacting with the C-terminal Phe of apelin, Phe255 and Trp259 in helix VI of the apelin receptor are critical for internalization. J. Biol. Chem. 285, 32627-32637
29. Galandrin, S., and Bouvier, M. (2006) Distinct signaling profiles of β1 and β2 adrenergic receptor ligands toward adenylyl cyclase and mitogen-activated protein kinase reveals the pluridimensionality of efficacy. Mol. Pharmacol. 70, 1575-1584
30. Galandrin, S., Oligny-Longpré, G., Bonin, H., Ogawa, K., Galés, C., and Bouvier, M. (2008) Conformational rearrangements and signaling cascades involved in ligand-biased mitogen-activated protein kinase signaling through the β1-adrenergic receptor. Mol. Pharmacol. 74, 162-172
31. Drake, M. T., Violin, J. D., Whalen, E. J., Wisler, J. W., Shenoy, S. K., and Lefkowitz, R. J. (2008) β-Arrestin-biased agonism at the β2-adrenergic receptor. J. Biol. Chem. 283, 5669-5676
32. Shukla, A. K., Violin, J. D., Whalen, E. J., Gesty-Palmer, D., Shenoy, S. K., and Lefkowitz, R. J. (2008) Distinct conformational changes in β-arrestin report biased agonism at seven-transmembrane receptors. Proc. Natl. Acad. Sci. U.S.A. 105, 9988-9993
33. Swaminath, G., Xiang, Y., Lee, T. W., Steenhuis, J., Parnot, C., and Kobilka, B. K. (2004) Sequential binding of agonists to the β2 adrenoceptor. Kinetic evidence for intermediate conformational states. J. Biol. Chem. 279, 686-691 (Pubitemid 38044873)
34. DeWire, S. M., Ahn, S., Lefkowitz, R. J., and Shenoy, S. K. (2007) β-Arrestins and cell signaling. Annu. Rev. Physiol. 69, 483-510
35. DeFea, K. A., Zalevsky, J., Thoma, M. S., Déry, O., Mullins, R. D., and Bunnett, N. W. (2000) β-Arrestin-dependent endocytosis of proteinase-activated receptor 2 is required for intracellular targeting of activated ERK1/2. J. Cell Biol. 148, 1267-1281
36. Hus-Citharel, A., Bouby, N., Frugière, A., Bodineau, L., Gasc, J. M., and Llorens-Cortes, C. (2008) Effect of apelin on glomerular hemodynamic function in the rat kidney. Kidney Int. 74, 486-494
37. Breton, B., Sauvageau, É., Zhou, J., Bonin, H., Le Gouill, C., and Bouvier, M. (2010) Multiplexing of multicolor bioluminescence resonance energy transfer. Biophys. J. 99, 4037-4046
38. Zimmerman, B., Beautrait, A., Aguila, B., Charles, R., Escher, E., Claing, A., Bouvier, M., and Laporte, S. A. (2012) Differential β-arrestin-dependent conformational signaling and cellular responses revealed by angiotensin analogs. Sci. Signal. 5, ra33
39. Galés, C., Rebois, R. V., Hogue, M., Trieu, P., Breit, A., Hébert, T. E., and Bouvier, M. (2005) Real-time monitoring of receptor and G-protein interactions in living cells. Nat. Methods 2, 177-184
40. Rochdi, M. D., Vargas, G. A., Carpentier, E., Oligny-Longpré, G., Chen, S., Kovoor, A., Gitelman, S. E., Rosenthal, S. M., von Zastrow, M., and Bouvier, M. (2010) Functional characterization of vasopressin type 2 receptor substitutions (R137H/C/L) leading to nephrogenic diabetes insipidus and nephrogenic syndrome of inappropriate antidiuresis: implications for treatments. Mol. Pharmacol. 77, 836-845
41. Black, J. W., and Leff, P. (1983) Operational models of pharmacological agonism. Proc. R. Soc. Lond. B Biol. Sci. 220, 141-162 (Pubitemid 14217337)
42. Evans, B. A., Broxton, N., Merlin, J., Sato, M., Hutchinson, D. S., Christopoulos, A., and Summers, R. J. (2011) Quantification of functional selectivity at the human α1A-adrenoceptor. Mol. Pharmacol. 79, 298-307
43. Kenakin, T., Watson, C., Muniz-Medina, V., Christopoulos, A., and Novick, S. (2012) A simple method for quantifying functional selectivity and agonist bias. ACS Chem. Neurosci. 3, 193-203
44. Kenakin, T., and Christopoulos, A. (2013) Signalling bias in new drug discovery: detection, quantification and therapeutic impact. Nat. Rev. Drug Discov. 12, 205-216
45. van der Westhuizen, E. T., Breton, B., Christopoulos, A., and Bouvier, M. (2014) Quantification of ligand bias for clinically relevant β2-adrenergic receptor ligands: implications for drug taxonomy. Mol. Pharmacol. 85, 492-509
46. Breton, B., Lagacé, M., and Bouvier, M. (2010) Combining resonance energy transfer methods reveals a complex between the β2A-adrenergic receptor, Gαi1β1γ2, and GRK2. FASEB J. 24, 4733-4743
47. Oakley, R. H., Laporte, S. A., Holt, J. A., Caron, M. G., and Barak, L. S. (2000) Differential affinities of visual arrestin, β arrestin1, and β arrestin2 for G protein-coupled receptors delineate two major classes of receptors. J. Biol. Chem. 275, 17201-17210 (Pubitemid 30398969)
48. Gesty-Palmer, D., Chen, M., Reiter, E., Ahn, S., Nelson, C. D., Wang, S., Eckhardt, A. E., Cowan, C. L., Spurney, R. F., Luttrell, L. M., and Lefkowitz, R. J. (2006) Distinct β-arrestin- and G protein-dependent pathways for parathyroid hormone receptor-stimulated ERK1/2 activation. J. Biol. Chem. 281, 10856-10864 (Pubitemid 43855508)
49. Tohgo, A., Choy, E. W., Gesty-Palmer, D., Pierce, K. L., Laporte, S., Oakley, R. H., Caron, M. G., Lefkowitz, R. J., and Luttrell, L. M. (2003) The stability of the G protein-coupled receptor-β-arrestin interaction determines the mechanism and functional consequence of ERK activation. J. Biol. Chem. 278, 6258-6267 (Pubitemid 36800882)
50. Luo, J., Busillo, J. M., and Benovic, J. L. (2008)M3muscarinic acetylcholine receptor-mediated signaling is regulated by distinct mechanisms. Mol. Pharmacol. 74, 338-347
51. Xu, T. R., Baillie, G. S., Bhari, N., Houslay, T. M., Pitt, A. M., Adams, D. R., Kolch, W., Houslay, M. D., and Milligan, G. (2008) Mutations of β-arrestin 2 that limit self-association also interfere with interactions with the β2- adrenoceptor and the ERK1/2 MAPKs: implications for β2-adrenoceptor signalling via the ERK1/2 MAPKs. Biochem. J. 413, 51-60 (Pubitemid 351946861)
52. Masri, B., Lahlou, H., Mazarguil, H., Knibiehler, B., and Audigier, Y. (2002) Apelin (65-77) activates extracellular signal-regulated kinases via a PTX-sensitive G protein. Biochem. Biophys. Res. Commun. 290, 539-545 (Pubitemid 34694535)
53. Charest, P. G., Oligny-Longpré, G., Bonin, H., Azzi, M., and Bouvier, M. (2007) The V2 vasopressin receptor stimulates ERK1/2 activity independently of heterotrimeric G protein signalling. Cell Signal. 19, 32-41
54. Shenoy, S. K., Drake, M. T., Nelson, C. D., Houtz, D. A., Xiao, K., Madabushi, S., Reiter, E., Premont, R. T., Lichtarge, O., and Lefkowitz, R. J. (2006) β-Arrestin-dependent, G protein-independent ERK1/2 activation by the β2 adrenergic receptor. J. Biol. Chem. 281, 1261-1273
55. Stalheim, L., Ding, Y., Gullapalli, A., Paing, M. M., Wolfe, B. L., Morris, D. R., and Trejo, J. (2005) Multiple independent functions of arrestins in the regulation of protease-activated receptor-2 signaling and trafficking. Mol. Pharmacol. 67, 78-87 (Pubitemid 40069968)
56. Tohgo, A., Pierce, K. L., Choy, E. W., Lefkowitz, R. J., and Luttrell, L. M. (2002) β-Arrestin scaffolding of the ERK cascade enhances cytosolic ERK activity but inhibits ERK-mediated transcription following angiotensin AT1a receptor stimulation. J. Biol. Chem. 277, 9429-9436
57. Wei, H., Ahn, S., Shenoy, S. K., Karnik, S. S., Hunyady, L., Luttrell, L. M., and Lefkowitz, R. J. (2003) Independent β-arrestin 2 and G protein-mediated pathways for angiotensin II activation of extracellular signal-regulated kinases 1 and 2. Proc. Natl. Acad. Sci. U.S.A. 100, 10782-10787 (Pubitemid 37140105)
58. Ahn, S., Shenoy, S. K., Wei, H., and Lefkowitz, R. J. (2004) Differential kinetic and spatial patterns of β-arrestin and G protein-mediated ERK activation by the angiotensin II receptor. J. Biol. Chem. 279, 35518-35525 (Pubitemid 39100552)
59. Granier, S., Kim, S., Shafer, A. M., Ratnala, V. R., Fung, J. J., Zare, R. N., and Kobilka, B. (2007) Structure and conformational changes in the C-terminal domain of the β2-adrenoceptor: insights from fluorescence resonance energy transfer studies. J. Biol. Chem. 282, 13895-13905 (Pubitemid 47100565)
60. Rahmeh, R., Damian, M., Cottet, M., Orcel, H., Mendre, C., Durroux, T., Sharma, K. S., Durand, G., Pucci, B., Trinquet, E., Zwier, J. M., Deupi, X., Bron, P., Banères, J. L., Mouillac, B., and Granier, S. (2012) Structural insights into biasedGprotein-coupled receptor signaling revealed by fluorescence spectroscopy. Proc. Natl. Acad. Sci. U.S.A. 109, 6733-6738
61. Rajagopal, K., Whalen, E. J., Violin, J. D., Stiber, J. A., Rosenberg, P. B., Premont, R. T., Coffman, T. M., Rockman, H. A., and Lefkowitz, R. J. (2006) β-Arrestin2-mediated inotropic effects of the angiotensin II type 1A receptor in isolated cardiac myocytes. Proc. Natl. Acad. Sci. U.S.A. 103, 16284-16289
62. Boerrigter, G., Lark, M. W., Whalen, E. J., Soergel, D. G., Violin, J. D., and Burnett, J. C., Jr. (2011) Cardiorenal actions of TRV120027, a novel β-arrestin-biased ligand at the angiotensin II type I receptor, in healthy and heart failure canines: a novel therapeutic strategy for acute heart failure. Circ Heart Fail. 4, 770-778
63. Violin, J. D., DeWire, S. M., Yamashita, D., Rominger, D. H., Nguyen, L., Schiller, K., Whalen, E. J., Gowen, M., and Lark, M. W. (2010) Selectively engaging β-arrestins at the angiotensin II type 1 receptor reduces blood pressure and increases cardiac performance. J. Pharmacol. Exp. Ther. 335, 572-579
64. Scimia, M. C., Hurtado, C., Ray, S., Metzler, S., Wei, K., Wang, J., Woods, C. E., Purcell, N. H., Catalucci, D., Akasaka, T., Bueno, O. F., Vlasuk, G. P., Kaliman, P., Bodmer, R., Smith, L. H., Ashley, E., Mercola, M., Brown, J. H., and Ruiz-Lozano, P. (2012) APJ acts as a dual receptor in cardiac hypertrophy. Nature 488, 394-398
65. Luttrell, L. M., Roudabush, F. L., Choy, E. W., Miller, W. E., Field, M. E., Pierce, K. L., and Lefkowitz, R. J. (2001) Activation and targeting of extracellular signal-regulated kinases by β-arrestin scaffolds. Proc. Natl. Acad. Sci. U.S.A. 98, 2449-2454 (Pubitemid 32209502)