scholarly journals Tiotidine, a Histamine H2 Receptor Inverse Agonist That Binds with High Affinity to an Inactive G-Protein—Coupled Form of the Receptor. Experimental Support for the Cubic Ternary Complex Model

2003 ◽  
Vol 64 (2) ◽  
pp. 512-520 ◽  
Author(s):  
Federico Monczor ◽  
Natalia Fernández ◽  
Bibiana Lemos Legnazzi ◽  
Maria Eugenia Riveiro ◽  
Alberto Baldi ◽  
...  
Keyword(s):  
G Protein ◽  
Ternary Complex ◽  
Complex Model ◽  
Histamine H2 Receptor ◽  
H2 Receptor ◽  
High Affinity ◽  
Experimental Support ◽  
Ternary Complex Model ◽  
G Protein Coupled ◽  
Receptor Inverse Agonist

scholarly journals Histamine H2 Receptor Desensitization: Involvement of a Select Array of G Protein-Coupled Receptor Kinases

2001 ◽  
Vol 60 (5) ◽  
pp. 1049-1056 ◽  
Author(s):  
Carina Shayo ◽  
Natalia Fernandez ◽  
Bibiana Lemos Legnazzi ◽  
Federico Monczor ◽  
Alejandro Mladovan ◽  
...  
Keyword(s):  
G Protein ◽  
Receptor Desensitization ◽  
G Protein Coupled Receptor ◽  
Histamine H2 Receptor ◽  
H2 Receptor ◽  
Receptor Kinases ◽  
G Protein Coupled

scholarly journals Structural and functional analysis of the canine histamine H2 receptor by site-directed mutagenesis: N-glycosylation is not vital for its action

1995 ◽  
Vol 310 (2) ◽  
pp. 553-558 ◽  
Author(s):  
Y Fukushima ◽  
Y Oka ◽  
T Saitoh ◽  
H Katagiri ◽  
T Asano ◽  
...  
Keyword(s):  
Molecular Mass ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Wild Type ◽  
Histamine H2 Receptor ◽  
H2 Receptor ◽  
H2 Receptors ◽  
G Protein Coupled

G-protein-coupled receptors generally share a similar structure containing seven membrane-spanning domains and extracellular site(s) for N-glycosylation. The histamine H2 receptor is a member of the family of G-protein-coupled receptors, and has three extracellular potential sites for N-glycosylation (Asn-4, Asn-162 and Asn-168). To date, however, no information has been presented regarding N-glycosylation of the H2 receptor. To investigate the presence, location and functional roles of N-glycosylation of the H2 receptor, site-directed mutagenesis was performed to eliminate the potential site(s) for N-glycosylation singly and collectively. The wild-type and mutated H2 receptors were expressed stably in Chinese hamster ovary (CHO) cells or transiently in COS7 cells. Immunoblotting of the wild-type and mutated H2 receptors with an antiserum directed against the C-terminus of the H2 receptor showed that mutation at Asn-162, but not at Asn-168, resulted in a substantial decrease in the molecular mass. A mutation at Asn-4 led to a further decrease in the molecular mass. Tunicamycin treatment of the transfected cells yielded a sharp band with a molecular mass identical to that of the mutant devoid of all three potential sites for N-glycosylation. These findings indicate that the H2 receptor is N-glycosylated, and that N-glycosylation takes place mainly at two sites, Asn-4 and Asn-162. Neither the affinity for tiotidine nor that for histamine was affected by the mutagenesis. Immunocytochemistry and tiotidine binding showed that the mutated receptors were exclusively distributed on the cell surface in a fashion similar to that of the wild-type. In addition, the glycosylation-defective receptor was capable of activating adenylate cyclase and elevating the intracellular Ca2+ concentration in response to histamine in stable CHO cell lines. Thus N-glycosylation of the H2 receptor is not required for cell surface localization, ligand binding or functional coupling to G-protein(s).

scholarly journals Roles of Phosphorylation-dependent and -independent Mechanisms in the Regulation of Histamine H2 Receptor by G Protein-coupled Receptor Kinase 2

2011 ◽  
Vol 286 (33) ◽  
pp. 28697-28706 ◽  
Author(s):  
Natalia Fernandez ◽  
Federico L. Gottardo ◽  
Maria N. Alonso ◽  
Federico Monczor ◽  
Carina Shayo ◽  
...  
Keyword(s):  
G Protein ◽  
Receptor Kinase ◽  
G Protein Coupled Receptor ◽  
Histamine H2 Receptor ◽  
H2 Receptor ◽  
G Protein Coupled

G protein-coupled prostaglandin receptor modulates conductive Na+ uptake in lung apical membrane vesicles

1998 ◽  
Vol 274 (4) ◽  
pp. L567-L572
Author(s):  
Somnath Mukhopadhyay ◽  
Asim K. Dutta-Roy ◽  
Gregor K. Fyfe ◽  
Richard E. Olver ◽  
Paul J. Kemp
Keyword(s):  
G Protein ◽  
Protein Function ◽  
Apical Membrane ◽  
Competitive Inhibition ◽  
Rank Order ◽  
Membrane Vesicles ◽  
High Affinity ◽  
High Affinity Binding Site ◽  
Uptake Studies ◽  
G Protein Coupled

Because G protein-regulated cation channels in type II pneumocytes constitute the most likely pathway for alveolar Na+ entry, we explored the hypothesis that a G protein-coupled prostaglandin (PG) E2 receptor controls perinatal lung alveolar Na+ transport. [3H]PGE2binding to the alveolar apical membrane was trypsin sensitive and showed a rank order of competitive inhibition: PGE2 = PGE1 > PGD2 > PGF2α. Kinetic analysis demonstrated both high-affinity [dissociation constant ( K D) = 2.1 ± 0.7 nM; maximal binding (Bmax) = 27 ± 7 fmol/mg protein] and low-affinity ( K D = 28 ± 2 nM; Bmax = 265 ± 29 fmol/mg protein) binding sites. Modulation of high-affinity GTPase activity identified a similar potency order (IC50 = 11 mM for PGF2α vs. 10–50 μM for other PGs), suggesting that the receptors are G protein coupled. Finally, 1 μM PGE2(≈IC25) increased conductive22Na+uptake into membrane vesicles only in the presence of 100 μM intravesicular GTP. The K D value for the high-affinity binding site together with the rank order of PG effect on ligand binding and G protein function places this PG receptor in the EP3 subtype, whereas Na+ uptake studies suggest that it helps maintain perinatal lung Na+homeostasis.

scholarly journals Specific oxylipins enhance vertebrate hematopoiesis via the receptor GPR132

2018 ◽  
Vol 115 (37) ◽  
pp. 9252-9257 ◽  
Author(s):  
Jamie L. Lahvic ◽  
Michelle Ammerman ◽  
Pulin Li ◽  
Megan C. Blair ◽  
Emma R. Stillman ◽  
...  
Keyword(s):  
Fatty Acids ◽  
G Protein ◽  
Cell Lines ◽  
Saturated Fatty Acids ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Hydroxy Fatty Acids ◽  
High Affinity ◽  
G Protein Coupled

Epoxyeicosatrienoic acids (EETs) are lipid-derived signaling molecules with cardioprotective and vasodilatory actions. We recently showed that 11,12-EET enhances hematopoietic induction and engraftment in mice and zebrafish. EETs are known to signal via G protein-coupled receptors, with evidence supporting the existence of a specific high-affinity receptor. Identification of a hematopoietic-specific EET receptor would enable genetic interrogation of EET signaling pathways, and perhaps clinical use of this molecule. We developed a bioinformatic approach to identify an EET receptor based on the expression of G protein-coupled receptors in cell lines with differential responses to EETs. We found 10 candidate EET receptors that are expressed in three EET-responsive cell lines, but not expressed in an EET-unresponsive line. Of these, only recombinant GPR132 showed EET-responsiveness in vitro, using a luminescence-based β-arrestin recruitment assay. Knockdown of zebrafish gpr132b prevented EET-induced hematopoiesis, and marrow from GPR132 knockout mice showed decreased long-term engraftment capability. In contrast to high-affinity EET receptors, GPR132 is reported to respond to additional hydroxy-fatty acids in vitro, and we found that these same hydroxy-fatty acids enhance hematopoiesis in the zebrafish. We conducted structure–activity relationship analyses using both cell culture and zebrafish assays on diverse medium-chain fatty acids. Certain oxygenated, unsaturated free fatty acids showed high activation of GPR132, whereas unoxygenated or saturated fatty acids had lower activity. Absence of the carbon-1 position carboxylic acid prevented activity, suggesting that this moiety is required for receptor activation. GPR132 responds to a select panel of oxygenated polyunsaturated fatty acids to enhance both embryonic and adult hematopoiesis.

Pharmacological characterization of putative β1-β2-adrenergic receptor heterodimers

2003 ◽  
Vol 81 (2) ◽  
pp. 186-195 ◽  
Author(s):  
Catherine Lavoie ◽  
Terence E Hébert
Keyword(s):  
G Protein ◽  
Receptor Subtypes ◽  
Affinity Binding ◽  
Pharmacological Characterization ◽  
High Affinity Binding ◽  
Hek 293 ◽  
High Affinity ◽  
High Affinity Binding Site ◽  
G Protein Coupled ◽  
Specific Ligand

In the last few years, significant experimental evidence has accumulated showing that many G protein coupled receptors (GPCRs) are structurally and perhaps functionally homodimers. Recently, a number of studies have demonstrated that many GPCRs, notably GABAB, somatostatin, and δ and κ opioid receptors form heterodimers, as well. Based on these observations, we undertook a pharmacological and functional analysis of HEK 293 cells transiently transfected with the β1AR or β2AR or with both subtypes together. High-affinity binding for subtype-specific ligands (betaxolol and xamoterol for the β1AR, and ICI 118,551 and procaterol for the β2AR) was detected in cells expressing the cognate receptors alone with values similar to those reported in the literature. However, a significant portion of these high-affinity interactions were lost when both receptors were expressed together while nonspecific ligands (propranolol and isoproterenol) retained their normal affinities. When competition assays were performed with each subtype-specific ligand in the presence of a constant concentration of the other subtype-specific ligand, the high-affinity binding site was rescued, suggesting that the two receptor subtypes were interacting in a fashion consistent with positive cooperativity. Our data suggest that the β1AR and β2AR can form heterodimers and that these receptors have altered pharmacological properties from the receptor homodimers.Key words: G protein coupled receptor, signalling, G protein, dimerization, heterodimer, adrenergic.

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