Estimation of Agonist Activity at G Protein-Coupled Receptors: Analysis of M2 Muscarinic Receptor Signaling through Gi/o,Gs, and G15

One mechanism for the reappearance of G protein-coupled receptors after agonist activation is microtubule-based transport. In pressure-overload cardiac hypertrophy, there is downregulation of G protein-coupled receptors and the appearance of a densified microtubule network extensively decorated by a microtubule-associated protein, MAP 4. Our hypothesis is that overdecoration of a dense microtubule network with this structural protein, as in hypertrophied myocardium, would impede receptor recovery. We tested this hypothesis by studying muscarinic acetylcholine receptor (mAChR) internalization and recovery after agonist stimulation in neuroblastoma cells. Exposure of cells to carbachol, a muscarinic receptor agonist, decreased membrane receptor binding activity. After carbachol withdrawal, receptor binding recovered toward the initial value. When microtubules were depolymerized before carbachol withdrawal, mAChR recovery was only 44% of that in intact cells. Cells were then infected with an adenovirus containing MAP 4 cDNA. MAP 4 protein decorated the microtubules extensively, and receptor recovery upon carbachol withdrawal was reduced to 54% of control. Thus muscarinic receptor recovery after agonist exposure is microtubule dependent, and MAP 4 decoration of microtubules inhibits receptor recovery.

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Drosophila GoLoco-Protein Pins Is a Target of Gαo-mediated G Protein–coupled Receptor Signaling

Molecular Biology of the Cell ◽

10.1091/mbc.e09-01-0021 ◽

2009 ◽

Vol 20 (17) ◽

pp. 3865-3877 ◽

Cited By ~ 28

Author(s):

Damir Kopein ◽

Vladimir L. Katanaev

Keyword(s):

G Protein ◽

System Development ◽

Nervous System Development ◽

G Protein Coupled Receptors ◽

Guanine Nucleotide ◽

Receptor Signaling ◽

Nucleotide Exchange ◽

Guanine Nucleotide Exchange ◽

Necessary And Sufficient ◽

G Protein Coupled

G protein–coupled receptors (GPCRs) transduce their signals through trimeric G proteins, inducing guanine nucleotide exchange on their Gα-subunits; the resulting Gα-GTP transmits the signal further inside the cell. GoLoco domains present in many proteins play important roles in multiple trimeric G protein–dependent activities, physically binding Gα-subunits of the Gαi/o class. In most cases GoLoco binds exclusively to the GDP-loaded form of the Gα-subunits. Here we demonstrate that the poly-GoLoco–containing protein Pins of Drosophila can bind to both GDP- and GTP-forms of Drosophila Gαo. We identify Pins GoLoco domain 1 as necessary and sufficient for this unusual interaction with Gαo-GTP. We further pinpoint a lysine residue located centrally in this domain as necessary for the interaction. Our studies thus identify Drosophila Pins as a target of Gαo-mediated GPCR receptor signaling, e.g., in the context of the nervous system development, where Gαo acts downstream from Frizzled and redundantly with Gαi to control the asymmetry of cell divisions.

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The complex role of Prostaglandin E2-EP receptor signaling in wound healing

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00185.2020 ◽

2020 ◽

Author(s):

Kristy E. Gilman ◽

Kirsten H. Limesand

Keyword(s):

Wound Healing ◽

G Protein ◽

Lipid Mediators ◽

G Protein Coupled Receptors ◽

Prostaglandin E ◽

Receptor Signaling ◽

Wound Healing Response ◽

Ep Receptor ◽

G Protein Coupled

Prostaglandins are critical lipid mediators involved in the wound healing response, with prostaglandin E2 (PGE2) being the most complex and exhibiting the most diverse physiological outputs. PGE2 signals via four G-protein coupled receptors, termed EP-receptors 1-4, that induce distinct signaling pathways upon activation and lead to an array of different outputs. Recent studies examining the role of PGE2 and EP receptor signaling in wound healing following various forms of tissue damage are discussed in this review.

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Mutational analysis of the m3 muscarinic receptor: Functional role of proline residues that are highly conserved among all G protein-coupled receptors

Life Sciences ◽

10.1016/0024-3205(93)90331-v ◽

1993 ◽

Vol 52 (5-6) ◽

pp. 557

Author(s):

J. Wess ◽

S. Nanavati ◽

Z. Vogel ◽

R. Maggio

Keyword(s):

G Protein ◽

Muscarinic Receptor ◽

Functional Role ◽

Mutational Analysis ◽

G Protein Coupled Receptors ◽

M3 Muscarinic Receptor ◽

G Protein Coupled

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Arrestins and Spinophilin Competitively Regulate Na+,K+-ATPase Trafficking through Association with a Large Cytoplasmic Loop of the Na+,K+-ATPase

Molecular Biology of the Cell ◽

10.1091/mbc.e06-08-0711 ◽

2007 ◽

Vol 18 (11) ◽

pp. 4508-4518 ◽

Cited By ~ 27

Author(s):

Tohru Kimura ◽

Patrick B. Allen ◽

Angus C. Nairn ◽

Michael J. Caplan

Keyword(s):

G Protein ◽

G Protein Coupled Receptors ◽

Receptor Signaling ◽

Cytoplasmic Loop ◽

Transfected Cells ◽

Cos Cells ◽

Intracellular Compartments ◽

G Protein Coupled ◽

In Cells

The activity and trafficking of the Na+,K+-ATPase are regulated by several hormones, including dopamine, vasopressin, and adrenergic hormones through the action of G-protein–coupled receptors (GPCRs). Arrestins, GPCR kinases (GRKs), 14-3-3 proteins, and spinophilin interact with GPCRs and modulate the duration and magnitude of receptor signaling. We have found that arrestin 2 and 3, GRK 2 and 3, 14-3-3 ε, and spinophilin directly associate with the Na+,K+-ATPase and that the associations with arrestins, GRKs, or 14-3-3 ε are blocked in the presence of spinophilin. In COS cells that overexpressed arrestin, the Na+,K+-ATPase was redistributed to intracellular compartments. This effect was not seen in mock-transfected cells or in cells expressing spinophilin. Furthermore, expression of spinophilin appeared to slow, whereas overexpression of β-arrestins accelerated internalization of the Na+,K+-ATPase endocytosis. We also find that GRKs phosphorylate the Na+,K+-ATPase in vitro on its large cytoplasmic loop. Taken together, it appears that association with arrestins, GRKs, 14-3-3 ε, and spinophilin may be important modulators of Na+,K+-ATPase trafficking.

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