Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GPCR”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed2006

The 7 TM G-protein-coupled receptor target family.

Chemical biology approaches have a long history in the exploration of the G-protein-coupled receptor (GPCR) family, which represents the largest and most important group of targets for therapeutics. The analysis of the human genome revealed a significant number of new members with unknown physiological function which are today the focus of many reverse pharmacology drug-discovery programs. As the seven hydrophobic transmembrane segments are a defining common structural feature of these receptors, and as signaling through heterotrimeric G proteins is not demonstrated in all cases, these proteins are also referred to as seven transmembrane (7 TM) or serpentine receptors. This review summarizes important historic milestones of GPCR research, from the beginning, when pharmacology was mainly descriptive, to the age of modern molecular biology, with the cloning of the first receptor and now the availability of the entire human GPCR repertoire at the sequence and protein level. It shows how GPCR-directed drug discovery was initially based on the careful testing of a few specifically made chemical compounds and is today pursued with modern drug-discovery approaches, including combinatorial library design, structural biology, molecular informatics, and advanced screening technologies for the identification of new compounds that activate or inhibit GPCRs specifically. Such compounds, in conjunction with other new technologies, allow us to study the role of receptors in physiology and medicine, and will hopefully result in novel therapies. We also outline how basic research on the signaling and regulatory mechanisms of GPCRs is advancing, leading to the discovery of new GPCR-interacting proteins and thus opening new perspectives for drug development. Practical examples from GPCR expression studies, HTS (high-throughput screening), and the design of monoamine-related GPCR-focused combinatorial libraries illustrate ongoing GPCR chemical biology research. Finally, we outline future progress that may relate today's discoveries to the development of new medicines.

Animals↗
PubMed1993

Identification, chromosomal location, and genome organization of mammalian G-protein-coupled receptors.

Vertebrate G-protein-coupled receptors are encoded by a diverse multigene family. Thirteen distinct G-protein-coupled receptors (Gpcr) were cloned from mouse germline cDNA following amplification in the polymerase chain reaction (PCR) with degenerate oligonucleotide primers complementary to the third and sixth transmembrane domains. Eleven Gpcr clones were mapped to single sites in the mouse genome following interspecific backcross analysis. One clone was mapped to two sites and another was not polymorphic in the cross and could not be mapped. Gpcr loci were well dispersed throughout the mouse genome and mapped to chromosomes 1, 2, 3, 4, 5, 8, 9, 10, 13, 17, and 18. Six Gpcr clones likely represent mouse homologs of already identified receptors, one Gpcr clone may identify a third type of IL-8 receptor, and three Gpcr clones appear to encode novel G-protein-coupled receptors. Further, three factor crosses and Southern blot analyses demonstrated that Gpcr16 maps proximally within the Spr deletion on mouse chromosome 1, near the Vil and Bcg loci. Human chromosomal locations for most Gpcr loci could be predicted based on linkage homologies that have been identified between human and mouse. Mapping additional G-protein-coupled receptors against the panel of murine interspecific backcrosses should expand our understanding of mammalian Gpcr gene evolution and genome organization.

Amino Acid Sequence↗
PubMed2006

erbB2 is required for G protein-coupled receptor signaling in the heart.

erbB2/Her2, a ligandless receptor kinase, has pleiotropic effects on mammalian development and human disease. The absence of erbB2 signaling in cardiac myocytes results in dilated cardiomyopathy in mice, resembling the cardiotoxic effects observed in a subset of breast cancer patients treated with the anti-Her2 antibody herceptin. Emerging evidence suggests that erbB2 is pivotal for integrating signaling networks involving multiple classes of extracellular signals. However, its role in G protein-coupled receptor (GPCR) signaling remains undefined. Because the activation of the MAPK pathway through GPCR signaling is important for cardiac homeostasis, we investigated whether erbB2 is required for GPCR-mediated MAPK signaling in wild-type and heart-specific erbB2 mutant mice. Here we demonstrate that erbB2, but not EGF receptor, is essential for MAPK activation induced by multiple GPCR agonists in cardiac myocytes. erbB2 is immunocomplexed with a GPCR in vivo and is transactivated after ligand treatment in vitro. Coexpression of erbB2 with GPCRs in heterologous cells results in ligand-dependent complex formation and MAPK activation. Furthermore, MAPK activation and cardiac contractility are markedly impaired in heart-specific erbB2 mutants infused with a GPCR agonist. These results reveal an essential mechanism requiring erbB2 as a coreceptor for GPCR signaling in the heart. The obligatory role of erbB2 in GPCR-dependent signaling may also be important in other cellular systems.

Animals↗
PubMed2001

Src and Pyk2 mediate G-protein-coupled receptor activation of epidermal growth factor receptor (EGFR) but are not required for coupling to the mitogen-activated protein (MAP) kinase signaling cascade.

The epidermal growth factor receptor (EGFR) and the non-receptor protein tyrosine kinases Src and Pyk2 have been implicated in linking a variety of G-protein-coupled receptors (GPCR) to the mitogen-activated protein (MAP) kinase signaling cascade. In this report we apply a genetic strategy using cells isolated from Src-, Pyk2-, or EGFR-deficient mice to explore the roles played by these protein tyrosine kinases in GPCR-induced activation of EGFR, Pyk2, and MAP kinase. We show that Src kinases are critical for activation of Pyk2 in response to GPCR-stimulation and that Pyk2 and Src are essential for GPCR-induced tyrosine phosphorylation of EGFR. By contrast, Pyk2, Src, and EGFR are dispensable for GPCR-induced activation of MAP kinase. Moreover, GPCR-induced MAP kinase activation is normal in fibroblasts deficient in both Src and Pyk2 (Src-/-Pyk2-/- cells) as well as in fibroblasts deficient in all three Src kinases expressed in these cells (Src-/-Yes-/-Fyn-/- cells). Finally, experiments are presented demonstrating that, upon stimulation of GPCR, activated Pyk2 forms a complex with Src, which in turn phosphorylates EGFR directly. These experiments reveal a role for Src kinases in Pyk2 activation and a role for Pyk2 and Src in tyrosine phosphorylation of EGFR following GPCR stimulation. In addition, EGFR, Src family kinases, and Pyk2 are not required for linking GPCRs with the MAP kinase signaling cascade.

Animals↗
PubMed2002

Cell-based high-throughput screening assay system for monitoring G protein-coupled receptor activation using beta-galactosidase enzyme complementation technology.

A novel cell-based functional assay to directly monitor G protein-coupled receptor (GPCR) activation in a high-throughput format, based on a common GPCR regulation mechanism, the interaction between beta-arrestin and ligand-activated GPCR, is described. A protein-protein interaction technology, the InteraX trade mark system, uses a pair of inactive beta-galactosidase (beta-gal) deletion mutants as fusion partners to the protein targets of interest. To monitor GPCR activation, stable cell lines expressing both GPCR- and beta-arrestin-beta-gal fusion proteins are generated. Following ligand stimulation, beta-arrestin binds to the activated GPCR, and this interaction drives functional complementation of the beta-gal mutant fragments. GPCR activation is measured directly by quantitating restored beta-gal activity. The authors have validated this assay system with two functionally divergent GPCRs: the beta2-adrenergic amine receptor and the CXCR2 chemokine-binding receptor. Both receptors are activated or blocked with known agonists and antagonists in a dose-dependent manner. The beta2-adrenergic receptor cell line was screened with the LOPAC trade mark compound library to identify both agonists and antagonists, validating this system for high-throughput screening performance in a 96-well microplate format. Hit specificity was confirmed by quantitating the level of cAMP. This assay system has also been performed in a high-density (384-well) microplate format. This system provides a specific, sensitive, and robust methodology for studying and screening GPCR-mediated signaling pathways.

Arrestins↗
PubMed2005

Confocal fluorescence microscopy for high-throughput screening of G-protein coupled receptors.

In the pharmaceutical industry, G-protein coupled receptors (GPCRs) are the most successful group of therapeutic targets. Finding compounds that interfere with the ligand-GPCR interaction in a specific and selective way is a major focus of pharmaceutical research today. As compound libraries of large pharmaceutical companies have increased to hundreds of thousands of test compounds, there is a growing need for miniaturization of drug discovery assays to save bioreagents and to reduce the consumption of test compounds. Due to its high sensitivity combined with a femtoliter-sized measurement volume, confocal fluorescence microscopy enables designs for GPCR binding assays with tiny sample volumes. The GPCRs are prepared in the form of plasma membrane fragments from GPCR-overexpressing cells or may be integrated into virus-like particles (VLiPs). One technique to extract binding data from confocal fluorescence experiments is the so-called fluorescence intensity distribution analysis (FIDA). In this review article, we describe the applicability of FIDA to GPCR-focussed high-throughput screening (HTS) and compare FIDA to two other GPCR-adaptable drug discovery techniques for ligand binding studies, the scintillation proximity assay (SPA) and macroscopic fluorescence polarization (FP) measurements. FIDA measures the absolute concentrations of both GPCR-bound and unbound ligand, thereby providing an internal control to the drug screening data. FIDA is amenable to work with relatively low amounts of GPCRs so that the assay may be carried out with biomembranes of a low GPCR density. Moreover, the fluorescence intensity readout of the FIDA technique may be combined with other confocal fluorescence readouts such as fluorescence anisotropy or lifetime. The combination of a low sample volume with an information-rich measurement means that confocal fluorescence spectroscopy can bring substantial benefits as a bioassay platform to pharmaceutical GPCR-directed research.

Animals↗
PubMed2004

G protein-coupled receptor agonist-stimulated expression of ATF3/LRF-1 and c-myc and comitogenic effects in hepatocytes do not require EGF receptor transactivation.

Several agonists acting on G protein-coupled receptors (GPCR) enhance the mitogenic effect of epidermal growth factor (EGF) in rat hepatocytes, through mechanisms that have only partially been clarified. Results in various cells have led to the idea that a major mechanism for GPCR-mediated stimulation of cell growth is transactivation of receptor tyrosine kinases, particularly the EGF receptor (EGFR), leading to rapid phosphorylation of the EGFR and activation of downstream signaling pathways. In the present study cultured rat hepatocytes were exposed to various GPCR agonists, including vasopressin, angiotensin II (Ang.II), norepinephrine, or prostaglandin F(2 alpha) (PGF(2 alpha)). None of these agents increased the phosphorylation of the EGFR or the docking protein Shc. Furthermore, we examined the effect of the GPCR agonists on the expression of two early response genes believed to be involved in growth activation. The GPCR agonists increased the mRNA expression of c-myc, and also of activating transcription factor 3 (ATF3)/liver regeneration factor-1 (LRF-1), which is a novel finding. Finally, the selective EGFR inhibitor AG1478 did not suppress the activation of extracellular signal-regulated kinase 1/2 (ERK1/2) or the induction of c-myc or ATF3/LRF-1 by the GPCR agonists, and did not prevent the comitogenic effects induced by these agents, while it blocked the effect of EGF on these responses. The results suggest that GPCR agonists induce expression of ATF3/LRF-1 and c-myc and exert comitogenic effects through mechanisms that do not require EGFR transactivation.

Activating Transcription Factor 3↗
PubMed2006

Chemogenomics approaches to G-protein coupled receptor lead finding.

G-protein coupled receptors (GPCRs) are promising targets for the discovery of novel drugs. In order to identify novel chemical series, high-throughput screening (HTS) is often complemented by rational chemogenomics lead finding approaches. We have compiled a GPCR directed screening set by ligand-based virtual screening of our corporate compound database. This set of compounds is supplemented with novel libraries synthesized around proprietary scaffolds. These target-directed libraries are designed using the knowledge of privileged fragments and pharmacophores to address specific GPCR subfamilies (e.g., purinergic or chemokine-binding GPCRs). Experimental testing of the GPCR collection has provided novel chemical series for several GPCR targets including the adenosine A1, the P2Y12, and the chemokine CCR1 receptor. In addition, GPCR sequence motifs linked to the recognition of GPCR ligands (termed chemoprints) are identified using homology modeling, molecular docking, and experimental profiling. These chemoprints can support the design and synthesis of compound libraries tailor-made for a novel GPCR target.

Animals↗
PubMed2002

Constitutive activity of G-protein-coupled receptors: cause of disease and common property of wild-type receptors.

The aim of this review is to provide a systematic overview on constitutively active G-protein-coupled receptors (GPCRs), a rapidly evolving area in signal transduction research. We will discuss mechanisms, pharmacological tools and methodological approaches to analyze constitutive activity. The two-state model defines constitutive activity as the ability of a GPCR to undergo agonist-independent isomerization from an inactive (R) state to an active (R*) state. While the two-state model explains basic concepts of constitutive GPCR activity and inverse agonism, there is increasing evidence for multiple active GPCR conformations with distinct biological activities. As a result of constitutive GPCR activity, basal G-protein activity increases. Until now, constitutive activity has been observed for more than 60 wild-type GPCRs from the families 1-3 and from different species including humans and commonly used laboratory animal species. Additionally, several naturally occurring and disease-causing GPCR mutants with increased constitutive activity relative to wild-type GPCRs have been identified. Alternative splicing, RNA editing, polymorphisms within a given species, species variants and coupling to specific G-proteins all modulate the constitutive activity of GPCRs, providing multiple regulatory switches to fine-tune basal cellular activities. The most important pharmacological tools to analyze constitutive activity are inverse agonists and Na(+) that stabilize the R state, and pertussis toxin that uncouples GPCRs from G(i)/G(o)-proteins. Constitutive activity is observed at low and high GPCR expression levels, in native systems and in recombinant systems, and has been reported for GPCRs coupled to G(s)-, G(i)- and G(q)-proteins. Constitutive activity of neurotransmitter GPCRs may provide a tonic support for basal neuronal activity. For the majority of GPCRs known to be constitutively active, inverse agonists have already been identified. Inverse agonists may be useful in the treatment of neuropsychiatric and cardiovascular diseases and of diseases caused by constitutively active GPCR mutants.

Animals↗
PubMed2004

Large-scale analysis of gene structure in rhodopsin-like GPCRs: evidence for widespread loss of an ancient intron.

The G-protein-coupled receptors (GPCRs) are a large superfamily of seven transmembrane domain-spanning proteins that mediate signal transduction by activation of G-proteins. Mammalian GPCR genes are reputed to be largely intron-deficient, but there have been no reports of using genome-wide analyses of gene structure to investigate this. Using complete genome sequences, we analysed the intron content of over 850 members of the rhodopsin-like GPCR subfamily (family A G-protein-coupled receptor or GPCR-A) in four species. We find that mouse and human GPCR-As have a large and significant reduction in intron number compared to the rest of their genome. In contrast, invertebrate GPCR-As have an intron repertoire similar to, or slightly greater than, the rest of their genome, suggesting that the reduced intron content in mammals is due to widespread intron loss. Furthermore, we provide a specific example of intron loss through analysis of an intron that is conserved in position and phase within a phylogenetically diverse range of GPCR-As within six vertebrate and invertebrate species. Together, these two lines of evidence provide compelling evidence for the widespread loss of introns during the evolution of the mammalian GPCR-A family.

Animals↗
PubMed2006

Air-stable G protein-coupled receptor microarrays and ligand binding characteristics.

This paper described novel strategies to achieve air-stable G protein-coupled receptor (GPCR) microarrays and the uses of the microarrays for ligand profiling. Specifically, GPCR cell membrane fragments were suspended in a buffered solution containing bovine serum albumin (BSA) and disaccharide sucrose or trehalose and used for fabricating GPCR microarrays. During the array fabrication and postfabrication processes, BSA molecules were found to effectively form packed layer(s) surrounding the GPCR membranes immobilized onto the predetermined printing area, thereby stabilizing the membrane microspots. The use of disaccharides was shown to protect the integrity and functionality of GPCR microarrays from the typical deterioration of the membranes when fabricated and stored under dry conditions. To utilize the ability of fluorescence technology for multichannel detection as well as to maximize the capability of GPCR microarrays for multiplexed binding assays, several fluorescently labeled ligands were synthesized and optimized for multiplexing binding assays. A schematic microarray of five GPCRs had been used as a model for characterizing the association and dissociation rate constants of labeled ligands binding to their respective receptors in the microarrays. Interestingly, distinct receptor-ligand interactions exhibited different dependence on the type of pH reagent as well as the species and concentration of cations used in a binding assay buffered solution. The potential mechanisms and implications for the uses of air-stable GPCR microarrays were discussed.

Air↗
PubMed1997

A beta-arrestin/green fluorescent protein biosensor for detecting G protein-coupled receptor activation.

G protein-coupled receptors (GPCR) represent the single most important drug targets for medical therapy, and information from genome sequencing and genomic data bases has substantially accelerated their discovery. The lack of a systematic approach either to identify the function of a new GPCR or to associate it with a cognate ligand has added to the growing number of orphan receptors. In this work we provide a novel approach to this problem using a beta-arrestin2/green fluorescent protein conjugate (betaarr2-GFP). It provides a real-time and single cell based assay to monitor GPCR activation and GPCR-G protein-coupled receptor kinase or GPCR-arrestin interactions. Confocal microscopy demonstrates the translocation of betaarr2-GFP to more than 15 different ligand-activated GPCRs. These data clearly support the common hypothesis that the beta-arrestin binding of an activated receptor is a convergent step of GPCR signaling, increase by 5-fold the number of GPCRs known to interact with beta-arrestins, demonstrate that the cytosol is the predominant reservoir of biologically active beta-arrestins, and provide the first direct demonstration of the critical importance of G protein-coupled receptor kinase phosphorylation to the biological regulation of beta-arrestin activity and GPCR signal transduction in living cells. The use of betaarr2-GFP as a biosensor to recognize the activation of pharmacologically distinct GPCRs should accelerate the identification of orphan receptors and permit the optical study of their signal transduction biology intractable to ordinary biochemical methods.

Animals↗
PubMed1999

The N terminus of Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor is necessary for high affinity chemokine binding but not for constitutive activity.

Kaposi's sarcoma-associated herpesvirus (KSHV) contains a gene encoding a G protein-coupled receptor (KSHV-GPCR) that is homologous to mammalian chemokine receptors. KSHV-GPCR signals constitutively (in an agonist-independent manner) via the phosphoinositide-inositol 1,4,5-trisphosphate pathway. Because it has been proposed that the N terminus (N-TERM) of other GPCRs may act as tethered agonists, we determined whether the N-TERM of KSHV-GPCR is necessary for constitutive signaling activity or ligand binding, or both. We show that replacement of the entire N-TERM of KSHV-GPCR with those of two other GPCRs, deletion of residues within the N-TERM, and disruption of a putative disulfide bond that may hold the N-TERM in close proximity to extracellular loop 3 do not affect constitutive signaling activity but decrease chemokine binding. There were differences in the effects of mutation of the N-TERM on binding of the chemokines growth-related oncogene alpha, which is an agonist, and interferon-gamma-inducible protein-10, which is an inverse agonist. The effects on chemokine binding were accompanied by changes in chemokine regulation of KSHV-GPCR signaling. We conclude that the N-TERM is not necessary for constitutive KSHV-GPCR signaling, i.e. the N-TERM is not a tethered agonist, but plays a crucial role in binding of chemokine ligands and of chemokine regulation of KSHV-GPCR signaling.

Animals↗
PubMed1998

Inhibition of constitutive signaling of Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor by protein kinases in mammalian cells in culture.

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8, which is consistently present in tissues of patients with Kaposi's sarcoma and primary effusion lymphomas, contains a gene that encodes a G protein-coupled receptor (KSHV-GPCR). We recently showed that KSHV-GPCR exhibits constitutive signaling via activation of phosphoinositide-specific phospholipase C and stimulates cell proliferation and transformation. In this study, we determined whether normal cellular mechanisms could inhibit constitutive signaling by KSHV-GPCR and thereby KSHV-GPCR-stimulated proliferation. We show that coexpression of GPCR-specific kinases (GRKs) and activation of protein kinase C inhibit constitutive signaling by KSHV-GPCR in COS-1 monkey kidney cells and in mouse NIH 3T3 cells. Moreover, GRK-5 but not GRK-2 inhibits KSHV-GPCR-stimulated proliferation of rodent fibroblasts. These data provide evidence that cell regulatory pathways of receptor desensitization may be therapeutic targets in human diseases involving constitutively active receptors.

3T3 Cells↗
PubMed2006

Diverse pathways for nuclear signaling by G protein-coupled receptors and their ligands.

Recent realization that plasma membrane G protein-coupled receptors (GPCRs) may translocate and establish ligand-responsive signaling complexes in other cellular structures has motivated studies of site-specific differences in transductional pathways. GPCRs and their ligands may signal transcription and other nuclear events by two basic mechanisms. The first consists of GPCR-complex activation of messengers that enter the nucleus and there initiate cell-modifying processes without the GPCR leaving the plasma membrane. The second encompasses entry into the nuclear membranes or matrix of either GPCR ligands, which bind to non-GPCR nuclear signaling proteins, proteolytic fragments of GPCRs capable of ligand-independent signaling, or intact GPCRs with transduction-competent factors that directly initiate or regulate transcriptional events. With the second mechanism, often concurrent down-regulation of plasma membrane GPCRs terminates signaling from the cell-surface and moves it into the nuclear domain. Site-dependent differences in signals from the same GPCR provide potentials for unique cellular abnormalities attributable to defective intracellular movement and distribution of a GPCR, site-specific alterations in ligand concentration, and limited intracellular bioavailability of pharmacological agents that can interact specifically with both nuclear and plasma membrane forms of a GPCR.

Animals↗
PubMed2002

Involvement of nuclear factor-kappaB and apoptosis signal-regulating kinase 1 in G-protein-coupled receptor agonist-induced cardiomyocyte hypertrophy.

BACKGROUND: Recently, reactive oxygen species (ROS) have emerged as important molecules in cardiac hypertrophy. However, the ROS-dependent signal transduction mechanism remains to be elucidated. In this study, we examined the role of an ROS-sensitive transcriptional factor, NF-kappaB, and a mitogen-activated protein kinase kinase kinase, apoptosis signal-regulating kinase 1 (ASK1), in G-protein-coupled receptor (GPCR) agonist (angiotensin II, endothelin-1, phenylephrine)-induced cardiac hypertrophy in isolated rat neonatal cardiomyocytes. METHODS AND RESULTS: Using an ROS-sensitive fluorescent dye, we observed an increase in fluorescence signal on addition of the GPCR agonists. The GPCR agonists induced NF-kappaB activation. Antioxidants such as N-acetyl cysteine, N-mercaptopropionyl glycine, and vitamin E attenuated the NF-kappaB activation. Infection of cardiomyocytes with an adenovirus expressing a degradation-resistant mutant of IkappaBalpha led to suppression of the hypertrophic responses. The GPCR agonists rapidly and transiently activated ASK1 in a dose-dependent manner. Infection of an adenovirus expressing a dominant-negative ASK1 attenuated the GPCR agonist-induced NF-kappaB activation and cardiac hypertrophy. Overexpression of a constitutively active mutant of ASK1 led to NF kappaB activation and cardiac hypertrophy. Activated ASK1-induced hypertrophy was abolished by inhibition of NF-kappaB activation. CONCLUSIONS: These data indicate that GPCR agonist-induced cardiac hypertrophy is mediated through NF-kappaB activation via the generation of ROS. ASK1 is involved in GPCR agonist-induced NF-kappaB activation and resulting hypertrophy.

Angiotensin II↗
PubMed1998

Chemokines activate Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor in mammalian cells in culture.

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8, a virus that appears to be involved in the pathogenesis of Kaposi's sarcoma and primary effusion lymphomas, encodes a G protein-coupled receptor (KSHV-GPCR) that exhibits constitutive signaling. In this report, we show that two chemokines, interleukin 8 (IL-8) and growth-related protein-alpha, activate KSHV-GPCR over constitutive levels. Moreover, as with human receptors, the integrity of the ELR motif of these chemokines is required for activation of KSHV-GPCR. Other residues that are required for IL-8 binding to human chemokine receptors CXCR1 and CXCR2 are important for KSHV-GPCR activation also. Thus, it appears that the ELR binding site and other key domains of ELR chemokine activation have been preserved in the virus KSHV-GPCR. The results suggest that KSHV-GPCR originated from CXCR1 or CXCR2 and that activation of KSHV-GPCR by endogenous chemokines may affect the pathobiology of KSHV infection in humans.

3T3 Cells↗
PubMed2001

Evolutionary relationships among G protein-coupled receptors using a clustered database approach.

Guanine nucleotide-binding protein-coupled receptors (GPCRs) comprise large and diverse gene families in fungi, plants, and the animal kingdom. GPCRs appear to share a common structure with 7 transmembrane segments, but sequence similarity is minimal among the most distant GPCRs. To reevaluate the question of evolutionary relationships among the disparate GPCR families, this study takes advantage of the dramatically increased number of cloned GPCRs. Sequences were selected from the National Center for Biotechnology Information (NCBI) nonredundant peptide database using iterative BLAST (Basic Local Alignment Search Tool) searches to yield a database of approximately 1700 GPCRs and unrelated membrane proteins as controls, divided into 34 distinct clusters. For each cluster, separate position-specific matrices were established to optimize sequence comparisons among GPCRs. This approach resulted in significant alignments between distant GPCR families, including receptors for the biogenic amine/peptide, VIP/secretin, cAMP, STE3/MAP3 fungal pheromones, latrophilin, developmental receptors frizzled and smoothened, as well as the more distant metabotrobic glutamate receptors, the STE2/MAM2 fungal pheromone receptors, and GPR1, a fungal glucose receptor. On the other hand, alignment scores between these recognized GPCR clades with p40 (putative GPCR) and pm1 (putative GPCR), as well as bacteriorhodopsins, failed to support a finding of homology. This study provides a refined view of GPCR ancestry and serves as a reference database with hyperlinks to other sources. Moreover, it may facilitate database annotation and the assignment of orphan receptors to GPCR families.

Amino Acid Sequence↗