Unimpaired coupling of phosphorylated, desensitized β‐adrenoceptor to G<sup>s</sup> in a reconstitution system

Keenan, A. K.; Cooney, Deirdre; Holzhöfer, Andreas; Dees, Christian; Hekman, Mirko

doi:10.1016/0014-5793(87)80680-4

Cited by 8 publications

(2 citation statements)

References 18 publications

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“…although it did not affect the interaction between non-phosphorylated rhodopsin and transducin (Wilden et al, 1986). In addition, Keenan et al (1987) reported recently that phosphorylated P-adrenergic receptors, which were purified from desensitized membranes with reduced receptor-(;, coupling, may couple with G, in a reconstituted system, and they suggested the contribution of a component(s) such as arrestin.…”

Section: Reconstitution Of Muscarinic Receptors and G Proteinsmentioning

confidence: 89%

Phosphorylation by Protein Kinase C of the Muscarinic Acetylcholine Receptor

Haga

Ichiyama

1990

Journal of Neurochemistry

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Muscarinic acetylcholine receptors purified from porcine cerebrum were phosphorylated by protein kinase C purified from the same tissue. More than 1 mol of phosphate was incorporated per mole of receptor, with both serine and threonine residues being phosphorylated. Neither the degree nor the rate of the phosphorylation was affected by the presence or absence of acetylcholine. GTP-sensitive high-affinity binding with acetylcholine was observed for muscarinic receptors reconstituted with GTP-binding proteins (Gi or Go), irrespective of whether muscarinic receptors or the GTP-binding proteins had been phosphorylated by protein kinase C or not. This indicates that the interaction between purified muscarinic receptors and purified GTP-binding proteins in vitro is not affected by their phosphorylation.

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Section: Reconstitution Of Muscarinic Receptors and G Proteinsmentioning

confidence: 89%

Phosphorylation by Protein Kinase C of the Muscarinic Acetylcholine Receptor

Haga

Ichiyama

1990

Journal of Neurochemistry

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“…For rhodopsin, RK phosphorylation alone inhibits coupling to G t , and the intrinsic inhibitory effects of phosphorylation on coupling are augmented by the addition of arrestin (13,14). But for the ␤ 2 AR, neither in vitro phosphorylation by ␤ARK (GRK2) (15,16) nor in vivo desensitization by agonist (17) has a large effect on reconstituted receptor coupling. In contrast, phosphorylation of the ␤ 2 AR by protein kinase A does deactivate the receptor (16), as does addition of ␤-arrestin to ␤ARK1-phosphorylated ␤ 2 AR (18).…”

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confidence: 99%

Phosphorylation Uncouples the Gastrin-releasing Peptide Receptor from Gq

Kroog¹,

Jian²,

Chen³

et al. 1999

Journal of Biological Chemistry

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Previous work on the desensitization of G proteincoupled receptors has focused on the role of arrestin binding following receptor phosphorylation. We have examined the hypothesis that phosphorylation alone contributes to desensitization. In this study we demonstrate that for the G q -coupled gastrin-releasing peptide receptor (GRP-R), phosphorylation by GRK2 to a stoichiometry of ϳ1 mol PO 4 /mol GRP-R is sufficient in the absence of arrestin to reduce the rate of receptor catalyzed G protein activation by approximately 80%. Furthermore, GRP-Rs exposed in vivo to agonist are rapidly phosphorylated to a similar stoichiometry and are desensitized to a similar degree. Finally, the molecular mechanism for both in vitro GRK2-induced and in vivo agonist-induced desensitization is primarily a decrease in the maximum velocity (V max ) for the catalysis of guanine nucleotide exchange by the GRP-R rather than a change in the affinity of the receptor for the ␣ q or ␤␥ subunits. Based on these results, we suggest that, for some G protein-coupled receptors, phosphorylation has a role in desensitization that is independent of arrestin.Bombesin-like peptides elicit a variety of effects including mitogenesis, hormone secretion, and modulation of neuron firing rate (1). These effects are transduced through a family of G protein-coupled receptors (GPCRs) 1 including the gastrin-releasing peptide receptor (GRP-R) (2, 3). An agonist-activated GPCR catalyzes the exchange of guanine nucleotide on the ␣ subunit of a heterotrimeric G protein leading to the formation of G␣-GTP. The subsequent dissociation of the heterotrimeric G protein leads to stimulation of signal transduction cascades mediated by the free G␣-GTP and G␤␥ subunits (4). In the bombesin receptor family, the activated GRP-R catalyzes guanine nucleotide exchange on G␣ q (5) to activate effectors including phospholipase C-␤ (3).Mechanisms to attenuate receptor signaling have evolved that limit the amplitude and/or duration of the signal transduction cascade(s) and are collectively referred to as "desensitization." At the molecular level, desensitization may result from the degradation of ligand, from changes in receptor availability or activity, or from changes in the availability or activity of downstream effector molecules (6). Rhodopsin, which signals through transducin (G t ), and the ␤ 2 -adrenergic receptor (␤ 2 AR), which signals through G s , have been the most extensively studied GPCRs. In both cases, rapid agonist-induced receptor phosphorylation along with subsequent binding of an arrestin to the receptor play critical roles in receptor deactivation (7,8). Many other GPCRs are also known to be rapidly phosphorylated after addition of agonist (9, 10), including the GRP-R (11). Two classes of protein kinase have been implicated in agonist-induced GPCR phosphorylation: 1) the second messenger-dependent protein kinases A and C and 2) the second messenger independent kinases, called G protein-coupled receptor kinases (GRKs), including rhodopsin kinase (RK or GRK1) an...

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