RGS domain in the amino-terminus of G protein-coupled receptor kinase 2 inhibits Gq-mediated signaling.

Usui, Hirokazu; Nishiyama, Mariko; Moroi, Kayoko; Shibasaki, Tadao; Zhou, Jing; Ishida, Junji; Fukamizu, Akiyoshi; Haga, Takashi; Sekiya, S; Kimura, Sadao

doi:10.3892/ijmm.5.4.335

Cited by 25 publications

(28 citation statements)

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“…92,93 In addition, the RGS domain of a kinase-inactivated mutant of GRK2 decreases endothelin-1 and Ang II signaling. 94 Such data suggest that GRK2 has a dual role, perhaps in serving as a negative RGS (via its GAP activity and its sequestration of G ␣ ) and in addition, as a receptor-desensitizing kinase for 2 ) is activated by the binding of ACh, which activates the associated G-proteins by catalyzing the exchange of GDP for GTP on the ␣-subunit. This causes the dissociation of the ␤␥-dimer, which binds and activates the K G channel.…”

Section: Grk2mentioning

confidence: 99%

Multi-Tasking RGS Proteins in the Heart

Riddle

Schwartzman²,

Bond³

et al. 2005

Circulation Research

112

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Abstract-Regulator of G-protein-signaling (RGS) proteins play a key role in the regulation of G-protein-coupled receptor(GPCR) signaling. The characteristic hallmark of RGS proteins is a conserved Ϸ120-aa RGS region that confers on these proteins the ability to serve as GTPase-activating proteins (GAPs) for G ␣ proteins. Most RGS proteins can serve as GAPs for multiple isoforms of G ␣ and therefore have the potential to influence many cellular signaling pathways. However, RGS proteins can be highly regulated and can demonstrate extreme specificity for a particular signaling pathway. RGS proteins can be regulated by altering their GAP activity or subcellular localization; such regulation is achieved by phosphorylation, palmitoylation, and interaction with protein and lipid-binding partners. Many RGS proteins have GAP-independent functions that influence GPCR and non-GPCR-mediated signaling, such as effector regulation or action as an effector. Hence, RGS proteins should be considered multifunctional signaling regulators. GPCR-mediated signaling is critical for normal function in the cardiovascular system and is currently the primary target for the pharmacological treatment of disease. Alterations in RGS protein levels, in particular RGS2 and RGS4, produce cardiovascular phenotypes. Thus, because of the importance of GPCR-signaling pathways and the profound influence of RGS proteins on these pathways, RGS proteins are regulators of cardiovascular physiology and potentially novel drug targets as well.

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Section: Grk2mentioning

confidence: 99%

Multi-Tasking RGS Proteins in the Heart

Riddle

Schwartzman²,

Bond³

et al. 2005

Circulation Research

112

View full text Add to dashboard Cite

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“…Although the mutated residues were spread over the entire NH 2 -terminal region, there are particularly high concentrations of mutations localized to the first 10 residues and to the central portion of the NH 2 -terminal domain (residues 72 to 87) suggesting the functional importance of these regions. Although GRK5 interaction with G␣ subunits has not been reported, this central region falls within the regulator of G protein signaling (RGS) homology domain in GRKs (encompassing residues ϳ40 -180 in GRK5) that mediates GRK2 interaction with G␣ q (31)(32)(33)(34). Glu-72, Pro-75, and Val-87 may be particularly important because multiple clones were identified with these residues mutated.…”

Section: Figmentioning

confidence: 99%

Development of a Yeast Bioassay to Characterize G Protein-coupled Receptor Kinases

Noble

Kallal

Pausch

et al. 2003

Journal of Biological Chemistry

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G protein-coupled receptor kinases (GRKs) specifically bind and phosphorylate the agonist-occupied form of G protein-coupled receptors. To further characterize the mechanism of GRK/receptor interaction, we developed a yeast-based bioassay using strains engineered to functionally express the somatostatin receptor subtype 2 and exhibit agonist-dependent growth. Here, we demonstrate that agonist-promoted growth was effectively inhibited by co-expression with either wild type GRK2 or GRK5, whereas catalytically inactive forms of these kinases were without effect. In an effort to identify residues involved in receptor interaction, we generated a pool of GRK5 mutants and then utilized the bioassay to identify mutants selectively deficient in inhibiting agonist-promoted growth. This resulted in the identification of a large number of mutants, several of which were expressed, purified, and characterized in more detail. Two of the mutants, GRK5-L3Q/K113R and GRK5-T10P, were defective in receptor phosphorylation and also exhibited a partial defect in phospholipid binding and phospholipid-stimulated autophosphorylation of the kinase. In contrast, these mutants had wild type activity in phosphorylating the non-receptor substrate tubulin. To further characterize the function of the NH 2 -terminal region of GRK5, we generated a deletion mutant lacking residues 2-14 and found that this mutant was also severely impaired in receptor phosphorylation and phospholipid-promoted autophosphorylation. In addition, an NH 2 -terminal 14-amino acid peptide from GRK5 selectively inhibited receptor phosphorylation by GRK5 but had minimal effect on GRK2 activity. Based on these findings, we propose a model whereby the extreme NH 2 terminus of GRK5 mediates phospholipid binding and is required for optimal receptor phosphorylation.A diverse array of extracellular stimuli transduce their signals through interaction with G protein-coupled receptors (GPCRs). 1 A critical process that occurs in most cells is the regulation of hormonal responsiveness, a phenomenon often termed desensitization. Whereas multiple mechanisms contribute to the regulation of GPCR function, G protein-coupled receptor kinases (GRKs) and arrestins play an important role in many cells (1-3). GRKs comprise a family of serine/threonine kinases that are uniquely able to associate with the agonistoccupied form of receptors (3-5). Signaling is terminated upon receptor phosphorylation and the subsequent binding of arrestins, effectively uncoupling receptor from G protein. Mammalian GRKs are classified into three subgroups according to their sequence homology: GRK1 and -7; GRK2 and -3; and GRK4, -5, and -6 (4 -6). GRKs share a common structural organization that includes a moderately conserved (ϳ20% identity) NH 2 -terminal domain of ϳ185 residues, a conserved (ϳ50% identity) central catalytic domain of ϳ330 residues, and a poorly conserved COOH-terminal domain of ϳ80 -180 residues (4, 5).An important feature of GRKs is their ability to specifically interact with activated receptor...

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“…Interestingly, c-Src phosphorylation also promotes the degradation of GRK2 via a process that is regulated by receptor stimulation and may involve GRK2 ubiquitination and targeting to the proteasome pathway (11). GRKs also interact with numerous additional proteins including G protein ␣ (12)(13)(14) and ␤␥ (15,16) subunits, clathrin (17), the GRK-interacting protein GIT1 (18), caveolin-1 (19), phosphoinositide 3-kinase-␣ and -␥ (20), cytoskeletal proteins such as tubulin and actin (21)(22)(23), and various calcium-binding proteins (reviewed in Ref. 24).…”

mentioning

confidence: 99%

G Protein-coupled Receptor Kinase Interaction with Hsp90 Mediates Kinase Maturation

Luo

Benovic

2003

Journal of Biological Chemistry

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G protein-coupled receptor kinase 2 (GRK2) is a serine/threonine-specific protein kinase that mediates agonist-dependent phosphorylation of numerous G protein-coupled receptors. In an effort to identify proteins that regulate GRK2 function, we searched for interacting proteins by immunoprecipitation of endogenous GRK2 from HL60 cells. Subsequent analysis by gel electrophoresis and mass spectrometry revealed that GRK2 associates with heat shock protein 90 (Hsp90). GRK2 interaction with Hsp90 was confirmed by co-immunoprecipitation and was effectively disrupted by geldanamycin, an Hsp90-specific inhibitor. Interestingly, geldanamycin treatment of HL60 cells decreased the expression of endogenous GRK2 in a dose-and time-dependent manner, and metabolic labeling demonstrated that geldanamycin rapidly accelerated the degradation of newly synthesized GRK2. The use of various protease inhibitors suggested that GRK2 degradation induced by geldanamycin was predominantly through the proteasome pathway. To test whether Hsp90 plays a general role in regulating GRK maturation, additional GRKs were studied by transient expression in COS-1 cells and subsequent treatment with geldanamycin. These studies demonstrate that GRK3, GRK5, and GRK6 are also stabilized by interaction with Hsp90. Taken together, our work revealed that GRK interaction with heat shock proteins plays an important role in regulating GRK maturation.

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RGS domain in the amino-terminus of G protein-coupled receptor kinase 2 inhibits Gq-mediated signaling.

Cited by 25 publications

References 0 publications

Multi-Tasking RGS Proteins in the Heart

Multi-Tasking RGS Proteins in the Heart

Development of a Yeast Bioassay to Characterize G Protein-coupled Receptor Kinases

G Protein-coupled Receptor Kinase Interaction with Hsp90 Mediates Kinase Maturation

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