Cong, Mei and Perry, Stepehn J. and Lin, Fang-Tsyr and Fraser, Iain D. and Hu, Liaoyuan A. and Chen, Wei and Pitcher, Julie A. and Scott, John D. and Lefkowitz, Robert J. (2001) Regulation of Membrane Targeting of the G Protein-coupled Receptor Kinase 2 by Protein Kinase A and Its Anchoring Protein AKAP79. Journal of Biological Chemistry, 276 (18). pp. 15192-15199. ISSN 0021-9258 http://resolver.caltech.edu/CaltechAUTHORS:CONjbc01
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The beta 2 adrenergic receptor (beta 2AR) undergoes desensitization by a process involving its phosphorylation by both protein kinase A (PKA) and G protein-coupled receptor kinases (GRKs). The protein kinase A-anchoring protein AKAP79 influences beta 2AR phosphorylation by complexing PKA with the receptor at the membrane. Here we show that AKAP79 also regulates the ability of GRK2 to phosphorylate agonist-occupied receptors. In human embryonic kidney 293 cells, overexpression of AKAP79 enhances agonist-induced phosphorylation of both the beta 2AR and a mutant of the receptor that cannot be phosphorylated by PKA (beta 2AR/PKA-). Mutants of AKAP79 that do not bind PKA or target to the beta 2AR markedly inhibit phosphorylation of beta 2AR/PKA-. We show that PKA directly phosphorylates GRK2 on serine 685. This modification increases Gbeta gamma subunit binding to GRK2 and thus enhances the ability of the kinase to translocate to the membrane and phosphorylate the receptor. Abrogation of the phosphorylation of serine 685 on GRK2 by mutagenesis (S685A) or by expression of a dominant negative AKAP79 mutant reduces GRK2-mediated translocation to beta 2AR and phosphorylation of agonist-occupied beta 2AR, thus reducing subsequent receptor internalization. Agonist-stimulated PKA-mediated phosphorylation of GRK2 may represent a mechanism for enhancing receptor phosphorylation and desensitization.
|Additional Information:||Copyright © 2001 by The American Society for Biochemistry and Molecular Biology, Inc. Received for publication, October 5, 2000, and in revised form, January 18, 2001. Published, JBC Papers in Press, January 22, 2001, DOI 10.1074/jbc.M009130200 We thank Drs. Randy A. Hall, Richard Premont, Audrey Claing for helpful discussion, Millie McAdams and Judy Phelps for DNA sequencing, and Donna Addison and Mary Holben for assistance with the preparation of this manuscript. This work was supported in part by National Institutes of Health Grants HL16037 (to R.J.L.) and GM48231 (to J.D.S). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. [J.D.S. and R.J.L. were] Investigators of the Howard Hughes Medical Institute.|
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|Deposited On:||29 Sep 2008 18:30|
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