scholarly journals Identification of a Transferable Two-Amino-Acid Motif (GT) Present in the C-Terminal Tail of the Human Lutropin Receptor that Redirects Internalized G Protein-Coupled Receptors from a Degradation to a Recycling Pathway

2003 ◽  
Vol 17 (3) ◽  
pp. 411-422 ◽  
Author(s):  
Colette Galet ◽  
Le Min ◽  
Ramesh Narayanan ◽  
Mikiko Kishi ◽  
Nancy L. Weigel ◽  
...  
Keyword(s):  
Amino Acid ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Amino Acid Motif ◽  
Lutropin Receptor ◽  
Recycling Pathway ◽  
G Protein Coupled

scholarly journals Minireview: Nutrient Sensing by G Protein-Coupled Receptors

2013 ◽  
Vol 27 (8) ◽  
pp. 1188-1197 ◽  
Author(s):  
Eric M. Wauson ◽  
Andrés Lorente-Rodríguez ◽  
Melanie H. Cobb
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
G Protein ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Nutrient Sensing ◽  
G Protein Coupled Receptors ◽  
Amino Acid Availability ◽  
Class C ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) are membrane proteins that recognize molecules in the extracellular milieu and transmit signals inside cells to regulate their behaviors. Ligands for many GPCRs are hormones or neurotransmitters that direct coordinated, stereotyped adaptive responses. Ligands for other GPCRs provide information to cells about the extracellular environment. Such information facilitates context-specific decision making that may be cell autonomous. Among ligands that are important for cellular decisions are amino acids, required for continued protein synthesis, as metabolic starting materials and energy sources. Amino acids are detected by a number of class C GPCRs. One cluster of amino acid-sensing class C GPCRs includes umami and sweet taste receptors, GPRC6A, and the calcium-sensing receptor. We have recently found that the umami taste receptor heterodimer T1R1/T1R3 is a sensor of amino acid availability that regulates the activity of the mammalian target of rapamycin. This review focuses on an array of findings on sensing amino acids and sweet molecules outside of neurons by this cluster of class C GPCRs and some of the physiologic processes regulated by them.

Characteristic amino acid combinations in olfactory G protein-coupled receptors

2007 ◽  
Vol 67 (1) ◽  
pp. 154-166
Author(s):  
Elena V. Samsonova ◽  
Peter Krause ◽  
Thomas Bäck ◽  
Ad P. IJzerman
Keyword(s):  
Amino Acid ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
G Protein Coupled

scholarly journals GPCRtm: An amino acid substitution matrix for the transmembrane region of class A G Protein-Coupled Receptors

2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Santiago Rios ◽  
Marta F. Fernandez ◽  
Gianluigi Caltabiano ◽  
Mercedes Campillo ◽  
Leonardo Pardo ◽  
...  
Keyword(s):  
Amino Acid ◽  
G Protein ◽  
Amino Acid Substitution ◽  
G Protein Coupled Receptors ◽  
Substitution Matrix ◽  
Transmembrane Region ◽  
Class A ◽  
Amino Acid Substitution Matrix ◽  
G Protein Coupled

scholarly journals Site-specific Incorporation of Keto Amino Acids into Functional G Protein-coupled Receptors Using Unnatural Amino Acid Mutagenesis

2007 ◽  
Vol 283 (3) ◽  
pp. 1525-1533 ◽  
Author(s):  
Shixin Ye ◽  
Caroline Köhrer ◽  
Thomas Huber ◽  
Manija Kazmi ◽  
Pallavi Sachdev ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
G Protein ◽  
Unnatural Amino Acids ◽  
Unnatural Amino Acid ◽  
G Protein Coupled Receptors ◽  
Calcium Flux ◽  
Unnatural Amino Acid Mutagenesis ◽  
Amino Acid Mutagenesis ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) are ubiquitous heptahelical transmembrane proteins involved in a wide variety of signaling pathways. The work described here on application of unnatural amino acid mutagenesis to two GPCRs, the chemokine receptor CCR5 (a major co-receptor for the human immunodeficiency virus) and rhodopsin (the visual photoreceptor), adds a new dimension to studies of GPCRs. We incorporated the unnatural amino acids p-acetyl-l-phenylalanine (Acp) and p-benzoyl-l-phenylalanine (Bzp) into CCR5 at high efficiency in mammalian cells to produce functional receptors harboring reactive keto groups at three specific positions. We obtained functional mutant CCR5, at levels up to ∼50% of wild type as judged by immunoblotting, cell surface expression, and ligand-dependent calcium flux. Rhodopsin containing Acp at three different sites was also purified in high yield (0.5–2 μg/107 cells) and reacted with fluorescein hydrazide in vitro to produce fluorescently labeled rhodopsin. The incorporation of reactive keto groups such as Acp or Bzp into GPCRs allows their reaction with different reagents to introduce a variety of spectroscopic and other probes. Bzp also provides the possibility of photo-cross-linking to identify precise sites of protein-protein interactions, including GPCR binding to G proteins and arrestins, and for understanding the molecular basis of ligand recognition by chemokine receptors.

scholarly journals IMMUNOLOGICAL INVESTIGATIONS OF HHV-6 U12 AND U51 ENCODED PROTEINS INVOLVEMENT IN AUTOIMMUNE THYROIDITIS DEVELOPMENT

2020 ◽  
Author(s):  
Alina Sultanova ◽  
Maksims Cistjakovs ◽  
Liba Sokolovska ◽  
Egils Cunskis ◽  
Modra Murovska
Keyword(s):  
Amino Acid ◽  
G Protein ◽  
Autoimmune Thyroiditis ◽  
Synthetic Peptides ◽  
Human Herpesvirus ◽  
Amino Acid Sequences ◽  
G Protein Coupled Receptors ◽  
Igm Antibodies ◽  
Specific Igg ◽  
G Protein Coupled

AbstractHuman herpesvirus 6 (HHV-6) is a human pathogen with a wide cell tropism and many immunomodulating properties. HHV-6 has been linked to the development of multiple diseases, among them – autoimmune. Conflicting evidence implicates HHV-6 in autoimmune thyroiditis (AIT). HHV-6 contains two genes (U12 and U51) that encode putative homologues of human G-protein-coupled receptors (GPCR) like CCR1, CCR3 and CCR5. It has been shown that proteins encoded by HHV-6 U12 and U51 genes can be expressed on the surface of epithelial and some peripheral blood mononuclear cells populations, which makes them a potential cause for evoking autoimmunity.The aim of this study was to identify potentially immunogenic synthetic peptides derived from HHV-6 U12 and U51 amino acid sequences and to find evidences of the possible involvement of these proteins in AIT development. 62 AIT patients positive for HHV-6 infection were enrolled in this study. 30 different synthetic peptides designed from HHV-6 U12 and U51 proteins’ amino acid sequences, as well as, recombinant human CCR1, CCR3 and CCR5 proteins were used for suspension multiplex immunological assay (SMIA) to detect specific IgG, and IgM antibodies.HHV-6 peptide specific IgG and IgM antibodies were found in patient’s samples, with higher signals for IgM antibodies, which is indicative of reactivation and active HHV-6 infection. As well recombinant CCR1 and CCR5 showed high signals on IgM antibodies which is indicating on the presence of potential auto-antibodies against human G protein-coupled receptors. No cross reactivity between HHV-6 peptide specific antibodies and human recombinant CCR1, CCR3 and CCR5 was found, however, the possibility of cross-reactive autoantibodies specific for structural epitopes cannot be excluded.

scholarly journals An Intracellular Loop (IL2) Residue Confers Different Basal Constitutive Activities to the Human Lutropin Receptor and Human Thyrotropin Receptor through Structural Communication between IL2 and Helix 6, via Helix 3

Endocrinology ◽  
2007 ◽  
Vol 149 (4) ◽  
pp. 1705-1717 ◽  
Author(s):  
Xiuyan Feng ◽  
Thomas Müller ◽  
Dario Mizrachi ◽  
Francesca Fanelli ◽  
Deborah L. Segaloff
Keyword(s):  
G Protein ◽  
Structural Model ◽  
G Protein Coupled Receptors ◽  
Receptor Expression ◽  
Cell Surface Receptor ◽  
Solvent Exposure ◽  
Lutropin Receptor ◽  
Reciprocal Arrangement ◽  
G Protein Coupled ◽  
Constitutively Active

The human lutropin receptor (hLHR) and human TSH receptor (hTSHR) are G protein-coupled receptors that play key roles in reproductive and thyroid physiology, respectively. We show using a quantitative assessment of cAMP production as a function of cell surface receptor expression that the hTSHR possesses greater basal constitutive activity than the hLHR. Further studies were undertaken to test the hypothesis that different potential Gs-coupling motifs identified in IL2 of the hTSHR and hLHR contribute to their different basal constitutive activities. Although mutating the receptors to interchange their potential Gs-coupling motifs reversed their relative activities, we show this to be due to the swapping of one IL2 residue (Q476 in the hLHR; R531 in the hTSHR). Molecular dynamics simulations show that the effect of the hLHR(Q476R) mutation, switching the structural features of the hLHR toward those of the hTSHR, is greater than the switching effect of the hTSHR(R531Q) mutant toward the hLHR. The structural model of the hLHR(Q476R) mutant can be considered as a hybrid of wild-type (wt) hTSHR and constitutively active mutant hLHR forms. In this hLHR(Q476R) mutant, IL2 adopts a structure similar to IL2 of the wt hTSHR, but it shares with the hLHR constitutively active mutant the solvent exposure and the reciprocal arrangement of helices 3, 5, and 6, including the weakening of the wt native R3.50-D6.30 interaction. Our results suggest a H3-mediated structural connection between IL2 and the cytosolic extension of H6. Thus, IL2 contributes significantly to the inactive and active state ensembles of these G protein-coupled receptors.

scholarly journals Molecular Characterization of PBAN G-protein Coupled Receptors in Moth Pest Species: Design of Antagonists

2012 ◽  
Author(s):  
Ada Rafaeli ◽  
Russell Jurenka
Keyword(s):  
Amino Acid ◽  
G Protein ◽  
Transcriptional Control ◽  
G Protein Coupled Receptors ◽  
Specific Amino Acid ◽  
Modeling Studies ◽  
Diapause Hormone ◽  
Moth Species ◽  
Peptide Agonist ◽  
G Protein Coupled

The proposed research was directed at determining the activation/binding domains and gene regulation of the PBAN-R’s thereby providing information for the design and screening of potential PBAN-R-blockers and to indicate possible ways of preventing the process from proceeding to its completion. Our specific aims included: (1) The identification of the PBAN-R binding domain by a combination of: (a) in silico modeling studies for identifying specific amino-acid side chains that are likely to be involved in binding PBAN with the receptor and; (b) bioassays to verify the modeling studies using mutant receptors, cell lines and pheromone glands (at tissue and organism levels) against selected, designed compounds to confirm if compounds are agonists or antagonists. (2) The elucidation ofthemolecular regulationmechanisms of PBAN-R by:(a) age-dependence of gene expression; (b) the effect of hormones and; (c) PBAN-R characterization in male hair-pencil complexes. Background to the topic Insects have several closely related G protein-coupled receptors (GPCRs) belonging to the pyrokinin/PBAN family, one with the ligand pheromone biosynthesis activating neuropeptide or pyrokinin-2 and another with diapause hormone or pyrokinin-1 as a ligand. We were unable to identify the diapause hormone receptor from Helicoverpa zea despite considerable effort. A third, related receptor is activated by a product of the capa gene, periviscerokinins. The pyrokinin/PBAN family of GPCRs and their ligands has been identified in various insects, such as Drosophila, several moth species, mosquitoes, Triboliumcastaneum, Apis mellifera, Nasoniavitripennis, and Acyrthosiphon pisum. Physiological functions of pyrokinin peptides include muscle contraction, whereas PBAN regulates pheromone production in moths plus other functions indicating the pleiotropic nature of these ligands. Based on the alignment of annotated genomic sequences, the primary and secondary structures of the pyrokinin/PBAN family of receptors have similarity with the corresponding structures of the capa or periviscerokinin receptors of insects and the neuromedin U receptors found in vertebrates. Major conclusions, solutions, achievements Evolutionary trace analysisof receptor extracellular domains exhibited several class-specific amino acid residues, which could indicate putative domains for activation of these receptors by ligand recognition and binding. Through site-directed point mutations, the 3rd extracellular domain of PBAN-R was shown to be critical for ligand selection. We identified three receptors that belong to the PBAN family of GPCRs and a partial sequence for the periviscerokinin receptor from the European corn borer, Ostrinianubilalis. Functional expression studies confirmed that only the C-variant of the PBAN-R is active. We identified a non-peptide agonist that will activate the PBAN-receptor from H. zea. We determined that there is transcriptional control of the PBAN-R in two moth species during the development of the pupa to adult, and we demonstrated that this transcriptional regulation is independent of juvenile hormone biosynthesis. This transcriptional control also occurs in male hair-pencil gland complexes of both moth species indicating a regulatory role for PBAN in males. Ultimate confirmation for PBAN's function in the male tissue was revealed through knockdown of the PBAN-R using RNAi-mediated gene-silencing. Implications, both scientific and agricultural The identification of a non-peptide agonist can be exploited in the future for the design of additional compounds that will activate the receptor and to elucidate the binding properties of this receptor. The increase in expression levels of the PBAN-R transcript was delineated to occur at a critical period of 5 hours post-eclosion and its regulation can now be studied. The mysterious role of PBAN in the males was elucidated by using a combination of physiological, biochemical and molecular genetics techniques.

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