G protein-coupled receptors (GPCRs) play stimulatory or modulatory roles in numerous physiological states and processes, including growth and development, vision, taste and olfaction, behavior and learning, emotion and mood, inflammation, and autonomic functions such as blood pressure, heart rate, and digestion. GPCRs constitute the largest protein superfamily in the human and are the largest target class for prescription drugs, yet most are poorly characterized, and of the more than 350 nonolfactory human GPCRs, over 100 are orphans for which no endogenous ligand has yet been convincingly identified. We here describe new live-cell assays that use recombinant GPCRs to quantify two general features of GPCR cell biology-receptor desensitization and resensitization. The assays employ a fluorogen-activating protein (FAP) reporter that reversibly complexes with either of two soluble organic molecules (fluorogens) whose fluorescence is strongly enhanced when complexed with the FAP. Both assays require no wash or cleanup steps and are readily performed in microwell plates, making them adaptable to high-throughput drug discovery applications.
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http://dx.doi.org/10.1177/1087057114534299 | DOI Listing |
Int J Mol Sci
May 2024
Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.
The N-terminal portion of the octapeptide angiotensin II (DRVYIHPF; AngII), a vasopressor peptide that favorably binds to, and activates, AngII type 1 receptor (ATR), has an important role in maintaining bioactive conformation. It involves all three charged groups, namely (i) the N-terminal amino group cation, (ii) the Asp sidechain anion and (iii) the Arg guanidino cation. Neutralization of any one of these three charged groups results in a substantial reduction (<5%) in bioactivity, implicating a specialized function for this cluster.
View Article and Find Full Text PDFToxicol Lett
July 2024
Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich, Jülich, Germany. Electronic address:
Desensitization of nicotinic acetylcholine receptors (nAChRs) can be induced by overstimulation with acetylcholine (ACh) caused by an insufficient degradation of ACh after poisoning with organophosphorus compounds (OPCs). Currently, there is no generally applicable treatment for OPC poisoning that directly targets the desensitized nAChR. The bispyridinium compound MB327, an allosteric modulator of nAChR, has been shown to act as a resensitizer of nAChRs, indicating that drugs binding directly to nAChRs can have beneficial effects after OPC poisoning.
View Article and Find Full Text PDFToxicol Lett
April 2024
Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany.
Intoxications with organophosphorus compounds (OPCs) effect a severe impairment of cholinergic neurotransmission that, as a result of overstimulation may lead to desensitization of nicotinic acetylcholine receptors (nAChRs) and finally to death due to respiratory paralysis. So far, therapeutics, that are capable to address and revert desensitized neuromuscular nAChRs into their resting, i.e.
View Article and Find Full Text PDFJ Cell Biol
April 2024
Department of Biochemistry, University of Washington, Seattle, WA, USA.
Inosine monophosphate dehydrogenase (IMPDH) is the rate-limiting enzyme in guanosine triphosphate (GTP) synthesis and assembles into filaments in cells, which desensitizes the enzyme to feedback inhibition and boosts nucleotide production. The vertebrate retina expresses two splice variants IMPDH1(546) and IMPDH1(595). In bovine retinas, residue S477 is preferentially phosphorylated in the dark, but the effects on IMPDH1 activity and regulation are unclear.
View Article and Find Full Text PDFγ-Aminobutyric acid type A receptors (GABARs) are members of the pentameric ligand-gated ion channel (pLGIC) family, which are widespread throughout the invertebrate and vertebrate central nervous system. GABARs are engaged in short-term changes of the neuronal concentrations of chloride (Cl) and bicarbonate (HCO ) ions by their passive permeability through the ion channel pore. GABARs are regulated by various structurally diverse phenolic substances ranging from simple phenols to complex polyphenols.
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