title: Assembly of an SAP97-AKAP79-cAMP-dependent protein kinase scaffold at the type 1 PSD-95/DLG/ZO1 motif of the human beta(1)-adrenergic receptor generates a receptosome involved in receptor recycling and networking.
abstract: Appropriate trafficking of the beta(1)-adrenergic receptor (beta(1)-AR) after agonist-promoted internalization is crucial for the resensitization of its signaling pathway. Efficient recycling of the beta(1)-AR required the binding of the protein kinase A anchoring protein-79 (AKAP79) to the carboxyl terminus of the beta(1)-AR (Gardner, L. A., Tavalin, S. A., Goehring, A., Scott, J. D., and Bahouth, S. W. (2006) J. Biol. Chem. 281, 33537-33553). In this study we show that AKAP79 forms a complex with the type 1 PDZ-binding sequence (ESKV) at the extreme carboxyl terminus of the beta(1)-AR, which is mediated by the membrane-associated guanylate kinase (MAGUK) protein SAP97. Thus, the PDZ and its associated SAP97-AKAP79 complex are involved in targeting the cyclic AMP-dependent protein kinase (PKA) to the beta(1)-AR. The PDZ and its scaffold were required for efficient recycling of the beta(1)-AR and for PKA-mediated phosphorylation of the beta(1)-AR at Ser(312). Overexpression of the catalytic subunit of PKA or mutagenesis of Ser(312) to the phosphoserine mimic aspartic acid both rescued the recycling of the trafficking-defective beta(1)-ARDelta PDZ mutant. Thus, trafficking signals transmitted from the PDZ-associated scaffold in the carboxyl terminus of the beta(1)-AR to Ser(312) in the 3rd intracellular loop (3rd IC) were paramount in setting the trafficking itinerary of the beta(1)-AR. The data presented here show that a novel beta(1)-adrenergic receptosome is organized at the beta(1)-AR PDZ to generate a scaffold essential for trafficking and networking of the beta(1)-AR.
authors.affiliation: Departments of Pharmacology and University of Tennessee Health Sciences Center, Memphis, Tennessee 38163.
authors.forename: Lidia A
authors.initials: LA
authors.lastname: Gardner
authors.affiliation: Physiology, the University of Tennessee Health Sciences Center, Memphis, Tennessee 38163.
authors.forename: Anjaparavanda P
authors.initials: AP
authors.lastname: Naren
authors.affiliation: Departments of Pharmacology and University of Tennessee Health Sciences Center, Memphis, Tennessee 38163. Electronic address: sbahouth@utmem.edu.
authors.forename: Suleiman W
authors.initials: SW
authors.lastname: Bahouth
mesh_terms: D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000074288:Discs Large Homolog 1 Protein; D011992:Endosomes / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D018342:Receptors, Adrenergic, beta-1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D054758:A Kinase Anchor Proteins; C487775:AKAP5 protein, human; D048868:Adaptor Proteins, Signal Transducing; C513314:DLG1 protein, human; D000074288:Discs Large Homolog 1 Protein; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D018342:Receptors, Adrenergic, beta-1; D017868:Cyclic AMP-Dependent Protein Kinases