1
|
Skiba M, Stolwijk JA, Wegener J. Label-free impedance measurements to unravel biomolecular interactions involved in G protein-coupled receptor signaling. Methods Cell Biol 2022; 169:221-236. [DOI: 10.1016/bs.mcb.2021.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
2
|
Newkirk ML, Rubenstein KJ, Kim JY, Labrecque CL, Airas J, Taylor CA, Evans HD, McKoy Q, Parish CA, Pollock JA. Analysis of MEMO1 Binding Specificity for ErbB2 Using Fluorescence Polarization and Molecular Dynamics Simulations. Biochemistry 2018; 57:5169-5181. [DOI: 10.1021/acs.biochem.8b00582] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Madeline L. Newkirk
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Kristen J. Rubenstein
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Jessica Y. Kim
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Courtney L. Labrecque
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Justin Airas
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Cooper A. Taylor
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Hunter D. Evans
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Quincy McKoy
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Carol A. Parish
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Julie A. Pollock
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| |
Collapse
|
3
|
Kumar BA, Kumari P, Sona C, Yadav PN. GloSensor assay for discovery of GPCR-selective ligands. Methods Cell Biol 2017; 142:27-50. [PMID: 28964338 DOI: 10.1016/bs.mcb.2017.07.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
G protein-coupled receptors (GPCRs) are modulators of almost every physiological process, and therefore, are most favorite therapeutic target for wide spectrum of diseases. Ideally, high-throughput functional assays should be implemented that allow the screening of large compound libraries in cost-effective manner to identify agonist, antagonist, and allosteric modulators in the same assay. Taking advantage of the increased understanding of the GPCR structure and signaling, several commercially available functional assays based on fluorescence or chemiluminescence detection are being used in both academia and industry. In this chapter, we provide step-by-step method and guidelines to perform cAMP measurement using GloSensor assay. Finally, we have also discussed the analysis and interpretation of results obtained using this assay by providing several examples of Gs- and Gi-coupled GPCRs.
Collapse
Affiliation(s)
- Boda Arun Kumar
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Poonam Kumari
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Chandan Sona
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Prem N Yadav
- Division of Pharmacology, CSIR-Central Drug Research Institute, Lucknow, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.
| |
Collapse
|
4
|
Boularan C, Gales C. Cardiac cAMP: production, hydrolysis, modulation and detection. Front Pharmacol 2015; 6:203. [PMID: 26483685 PMCID: PMC4589651 DOI: 10.3389/fphar.2015.00203] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 09/03/2015] [Indexed: 01/04/2023] Open
Abstract
Cyclic adenosine 3′,5′-monophosphate (cAMP) modulates a broad range of biological processes including the regulation of cardiac myocyte contractile function where it constitutes the main second messenger for β-adrenergic receptors' signaling to fulfill positive chronotropic, inotropic and lusitropic effects. A growing number of studies pinpoint the role of spatial organization of the cAMP signaling as an essential mechanism to regulate cAMP outcomes in cardiac physiology. Here, we will briefly discuss the complexity of cAMP synthesis and degradation in the cardiac context, describe the way to detect it and review the main pharmacological arsenal to modulate its availability.
Collapse
Affiliation(s)
- Cédric Boularan
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier Toulouse, France
| | - Céline Gales
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier Toulouse, France
| |
Collapse
|
5
|
A cell-based, high-throughput homogeneous time-resolved fluorescence assay for the screening of potential κ-opioid receptor agonists. Acta Pharmacol Sin 2014; 35:957-66. [PMID: 24930486 DOI: 10.1038/aps.2014.21] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 01/22/2014] [Indexed: 11/08/2022] Open
Abstract
AIM The aim of this study was to identify κ-opioid receptor (KOR) agonists from a library of 80 000 small-molecule compounds and provide the experimental basis for the development of new analgesic candidates. METHODS The cell-based, high-throughput screen for human KOR agonists was based on the LANCE cAMP assay. Preliminary structure-activity relationship (SAR) analysis was applied according to the compounds' structures. An acetic acid twisting experiment was used to verify the pharmacodynamics. RESULTS In total, 31 compounds were identified as KOR agonists after preliminary and secondary screening. Of these compounds, five demonstrated significant KOR-stimulating activity that was comparable to U-50,488, a selective KOR agonist. The EC50 values for I-7, I-8, I-10, II-5, and II-8 were 13.34 ± 1.65, 14.01 ± 1.84, 9.57 ± 0.19, 14.94 ± 0.64, and 8.74 ± 0.72 nmol/L, respectively. Based on SAR studies, the stimulating activity of compounds with 5-phenyl-7-(trifluoromethyl)-4,5,6,7-tetrahydropyrazolo [1, 5-a] pyrimidine (group I) and 3,4-dimethoxy-N-(2-oxoethyl)-N-p-tolylbenzenesulfonamide (group II) parent structures were higher than the compound with a 5-hydroxy-2-methylbenzofuran-3-carboxylic acid (group III) parent structure. Pharmacodynamic experiments indicated that 20-40 μg/kg ip of compounds I-10 and II-8 significantly decreased the number of writhes induced by acetic acid; this finding is consistent with the SAR studies. Furthermore, the analgesic effects of compounds I-10 and II-8 were significantly antagonized in the presence of the selective KOR antagonist nor-BNI. CONCLUSION These findings collectively indicate that compounds I-10 and II-8 exhibit significant analgesic activities, providing evidence, at least in part, for their clinical application as new analgesic drugs.
Collapse
|
6
|
Martikkala E, Rozwandowicz-Jansen A, Hänninen P, Petäjä-Repo U, Härmä H. A homogeneous single-label time-resolved fluorescence cAMP assay. ACTA ACUST UNITED AC 2011; 16:356-62. [PMID: 21343601 DOI: 10.1177/1087057110397356] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
G-protein-coupled receptors (GPCRs) are an important class of pharmaceutical drug targets. Functional high-throughput GPCR assays are needed to test an increasing number of synthesized novel drug compounds and their function in signal transduction processes. Measurement of changes in the cyclic adenosine monophosphate (cAMP) concentration is a widely used method to verify GPCR activation in the adenylyl cyclase pathway. Here, a single-label time-resolved fluorescence and high-throughput screening (HTS)-feasible method was developed to measure changes in cAMP levels in HEK293(i) cells overexpressing either β(2)-adrenergic or δ-opioid receptors. In the quenching resonance energy transfer (QRET) technique, soluble quenchers reduce the signal of unbound europium(III)-labeled cAMP in solution, whereas the antibody-bound fraction is fluorescent. The feasibility of this homogeneous competitive assay was proven by agonist-mediated stimulation of receptors coupled to either the stimulatory G(s) or inhibitory G(i) proteins. The reproducibility of the assays was excellent, and Z' values exceeded 0.7. The dynamic range, signal-to-background ratio, and detection limit were compared with a commercial time-resolved fluorescence resonance energy transfer (TR-FRET) assay. In both homogeneous assays, similar assay parameters were obtained when adenylyl cyclase was stimulated directly by forskolin or via agonist-mediated activation of the G(s)-coupled β(2)AR. The advantage of using the single-label approach relates to the cost-effectiveness of the QRET system compared with the two-label TR-FRET assay as there is no need for labeling of two binding partners leading to reduced requirements for assay optimization.
Collapse
Affiliation(s)
- Eija Martikkala
- Laboratory of Biophysics and Medicity, University of Turku, Turku, Finland.
| | | | | | | | | |
Collapse
|
7
|
Liu K, Titus S, Southall N, Zhu P, Inglese J, Austin CP, Zheng W. Comparison on functional assays for Gq-coupled GPCRs by measuring inositol monophospate-1 and intracellular calcium in 1536-well plate format. CURRENT CHEMICAL GENOMICS 2008; 1:70-8. [PMID: 20161830 PMCID: PMC2774619 DOI: 10.2174/1875397300801010070] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 05/17/2008] [Accepted: 05/21/2008] [Indexed: 12/15/2022]
Abstract
Cell-based functional assays used for compound screening and lead optimization play an important role in drug discovery for G-protein coupled receptors (GPCRs). Cell-based assays can define the role of a compound as an agonist, antagonist or inverse agonist and can provide detailed information about the potency and efficacy of a compound. In addition, cell-based screens can be used to identify allosteric modulators that interact with sites other than the binding site of the endogenous ligand. Intracellular calcium assays which use a fluorescent calcium binding dye (such as Fluo-3, Fluo-4 or Fura-2) have been used in compound screening campaigns to measure the activity of Gq-coupled GPCRs. However, such screening methodologies require a special instrumentation to record the rapid change in intracellular free calcium concentration over time. The radioactive inositol 1,4,5- triphosphate (IP(3)) assay measures (3)H-inositol incorporation and is another traditional assay for the assessment of Gq-coupled GPCR activity, but it is not suitable for screening of large size compound collections because it requires a cell wash step and generates radioactive waste. To avoid these limitations, we have optimized and miniaturized a TR-FRET based IP-One assay that measures inositol monophosphate in a 1536-well plate format. This assay is homogenous, non-radioactive and does not require a kinetic readout. It has been tested with the cell lines expressing M(1) acetylcholine, FFAR1, vasopressin V1b, or Neuropeptide S receptors. The activities of antagonists determined in the IP-One assay correlated well with these measured in the intracellular calcium assay while the correlation of agonist activities might vary from cell line to cell line. This IP-One assay offers an alternative method for high throughput screening of Gq-coupled GPCRs without using costly kinetic plate readers.
Collapse
Affiliation(s)
- Ke Liu
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3370, USA
| | | | | | | | | | | | | |
Collapse
|
8
|
Kimple AJ, Yasgar A, Hughes M, Jadhav A, Willard FS, Muller RE, Austin CP, Inglese J, Ibeanu GC, Siderovski DP, Simeonov A. A high throughput fluorescence polarization assay for inhibitors of the GoLoco motif/G-alpha interaction. Comb Chem High Throughput Screen 2008; 11:396-409. [PMID: 18537560 DOI: 10.2174/138620708784534770] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The GoLoco motif is a short Galpha-binding polypeptide sequence. It is often found in proteins that regulate cell-surface receptor signaling, such as RGS12, as well as in proteins that regulate mitotic spindle orientation and force generation during cell division, such as GPSM2/LGN. Here, we describe a high throughput fluorescence polarization (FP) assay using fluorophore-labeled GoLoco motif peptides for identifying inhibitors of the GoLoco motif interaction with the G-protein alpha subunit Galpha (i1). The assay exhibits considerable stability over time and is tolerant to DMSO up to 5%. The Z'-factors for robustness of the GPSM2 and RGS12 GoLoco motif assays in a 96-well plate format were determined to be 0.81 and 0.84, respectively; the latter assay was run in a 384-well plate format and produced a Z'-factor of 0.80. To determine the screening factor window (Z-factor) of the RGS12 GoLoco motif screen using a small molecule library, the NCI Diversity Set was screened. The Z-factor was determined to be 0.66, suggesting that this FP assay would perform well when developed for 1,536-well format and scaled up to larger libraries. We then miniaturized to a 4 microL final volume a pair of FP assays utilizing fluorescein- (green) and rhodamine- (red) labeled RGS12 GoLoco motif peptides. In a fully-automated run, the Sigma-Aldrich LOPAC(1280) collection was screened three times with every library compound being tested over a range of concentrations following the quantitative high throughput screening (qHTS) paradigm; excellent assay performance was noted with average Z-factors of 0.84 and 0.66 for the green- and red-label assays, respectively.
Collapse
Affiliation(s)
- Adam J Kimple
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3370, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Kool J, van Marle A, Hulscher S, Selman M, van Iperen DJ, van Altena K, Gillard M, Bakker RA, Irth H, Leurs R, Vermeulen NPE. A flow-through fluorescence polarization detection system for measuring GPCR-mediated modulation of cAMP production. ACTA ACUST UNITED AC 2008; 12:1074-83. [PMID: 18087072 DOI: 10.1177/1087057107308881] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A flow-through fluorescence polarization (FP) detection system that makes use of a novel high-performance liquid chromatography (HPLC) fluorescence detector modified with polarization filters was developed. This flow-through FP detection system was evaluated by using a novel and very cost-effective bioassay for cyclic adenosine monophosphate (cAMP). The bioassay was first evaluated and optimized in an FP plate reader format and subsequently in a flow-through bioassay setup. The principle of the bioassay is based on the competition of cAMP and a fluorescent cAMP derivative for the cAMP binding domain of protein kinase A. cAMP could accurately be determined over a range of 0.8 to 30 pmol/well in the plate reader FP assay and over a range of 0.3 to 50 pmol/well in the flow-through FP assay setup. High Z' factors (i.e., 0.89 for the plate reader and 0.93 for the flow-through FP cAMP assay, respectively) indicated robust assays. Finally, functional cAMP signaling of the human histamine H(3) G-protein-coupled receptor (GPCR) in cell cultures was measured with both assay formats with good sensitivities and assay windows. The pEC(50) values obtained in both assay formats were in accordance with those obtained with standard methods. The flow-through FP detection system could thus be used as a cost-effective alternative to FP plate reader assays. Moreover, the novel flow-through FP detection system for cAMP constitutes a good analytical tool to be used in the GPCR research field as an alternative to the use of FP plate readers or radioactive laboratories nowadays used for cAMP measurements.
Collapse
Affiliation(s)
- Jeroen Kool
- LACDR-Division of Molecular Toxicology, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Hawkes C, Amritraj A, Macdonald RG, Jhamandas JH, Kar S. Heterotrimeric G proteins and the single-transmembrane domain IGF-II/M6P receptor: functional interaction and relevance to cell signaling. Mol Neurobiol 2008; 35:329-45. [PMID: 17917122 DOI: 10.1007/s12035-007-0021-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 11/30/1999] [Accepted: 04/02/2007] [Indexed: 12/11/2022]
Abstract
The G protein-coupled receptor (GPCR) family represents the largest and most versatile group of cell surface receptors. Classical GPCR signaling constitutes ligand binding to a seven-transmembrane domain receptor, receptor interaction with a heterotrimeric G protein, and the subsequent activation or inhibition of downstream intracellular effectors to mediate a cellular response. However, recent reports on direct, receptor-independent G protein activation, G protein-independent signaling by GPCRs, and signaling of nonheptahelical receptors via trimeric G proteins have highlighted the intrinsic complexities of G protein signaling mechanisms. The insulin-like growth factor-II/mannose-6 phosphate (IGF-II/M6P) receptor is a single-transmembrane glycoprotein whose principal function is the intracellular transport of lysosomal enzymes. In addition, the receptor also mediates some biological effects in response to IGF-II binding in both neuronal and nonneuronal systems. Multidisciplinary efforts to elucidate the intracellular signaling pathways that underlie these effects have generated data to suggest that the IGF-II/M6P receptor might mediate transmembrane signaling via a G protein-coupled mechanism. The purpose of this review is to outline the characteristics of traditional and nontraditional GPCRs, to relate the IGF-II/M6P receptor's structure with its role in G protein-coupled signaling and to summarize evidence gathered over the years regarding the putative signaling of the IGF-II/M6P receptor mediated by a G protein.
Collapse
Affiliation(s)
- C Hawkes
- Department of Psychiatry, Centre for Alzheimer and Neurodegenerative Research, University of Alberta, Edmonton, AB, T6G 2B7, Canada
| | | | | | | | | |
Collapse
|
11
|
Titus S, Neumann S, Zheng W, Southall N, Michael S, Klumpp C, Yasgar A, Shinn P, Thomas CJ, Inglese J, Gershengorn MC, Austin CP. Quantitative high-throughput screening using a live-cell cAMP assay identifies small-molecule agonists of the TSH receptor. ACTA ACUST UNITED AC 2008; 13:120-7. [PMID: 18216391 DOI: 10.1177/1087057107313786] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The thyroid-stimulating hormone (TSH; thyrotropin) receptor belongs to the glycoprotein hormone receptor subfamily of 7-transmembrane spanning receptors. TSH receptor (TSHR) is expressed mainly in thyroid follicular cells and is activated by TSH, which regulates the growth and function of thyroid follicular cells. Recombinant TSH is used in diagnostic screens for thyroid cancer, especially in patients after thyroid cancer surgery. Currently, no selective small-molecule agonists of the TSHR are available. To screen for novel TSHR agonists, the authors miniaturized a commercially available cell-based cyclic adenosine 3',5' monophosphate (cAMP) assay into a 1536-well plate format. This assay uses an HEK293 cell line stably transfected with the TSHR coupled to a cyclic nucleotide gated ion channel as a biosensor. From a quantitative high-throughput screen of 73,180 compounds in parallel with a parental cell line (without the TSHR), 276 primary active compounds were identified. The activities of the selected active compounds were further confirmed in an orthogonal homogeneous time-resolved fluorescence cAMP-based assay. Forty-nine compounds in several structural classes have been confirmed as the small-molecule TSHR agonists that will serve as a starting point for chemical optimization and studies of thyroid physiology in health and disease.
Collapse
Affiliation(s)
- Steve Titus
- National Institutes of Health Chemical Genomics Center, National Human Genome Research Institute, NIH, Bethesda, MD 20892-3370, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Tang Y, Li X, Han X, Lu J, Diwu Z. Functional analysis of endogenous beta-adrenergic receptor through fluorimetric monitoring of cyclic nucleotide-gated ion channel. Anal Biochem 2006; 360:303-5. [PMID: 17145040 DOI: 10.1016/j.ab.2006.04.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 04/22/2006] [Accepted: 04/25/2006] [Indexed: 11/21/2022]
Affiliation(s)
- Yi Tang
- AnaSpec Inc., San Jose, CA 95131, USA
| | | | | | | | | |
Collapse
|
13
|
Glover CJ, Hite K, DeLosh R, Scudiero DA, Fivash MJ, Smith LR, Fisher RJ, Wu JW, Shi Y, Kipp RA, McLendon GL, Sausville EA, Shoemaker RH. A high-throughput screen for identification of molecular mimics of Smac/DIABLO utilizing a fluorescence polarization assay. Anal Biochem 2003; 320:157-69. [PMID: 12927820 DOI: 10.1016/s0003-2697(03)00389-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Resistance to apoptosis is afforded by inhibitor of apoptosis proteins (IAPs) which bind to and inhibit the caspases responsible for cleavage of substrates leading to apoptotic cell death. Smac (or DIABLO), a proapoptotic protein released from the mitochondrial intermembrane space into the cytosol, promotes apoptosis by binding to IAPs, thus reversing their inhibitory effects on caspases. We have developed a high-throughput fluorescence polarization assay utilizing a fluorescein-labeled peptide similar to the "IAP binding" domain of Smac N terminus complexed with the BIR3 domain of X-linked IAP (XIAP) to identify small-molecule mimics of the action of Smac. The IC(50)s of peptides and a tetrapeptidomimetic homologous to the N terminus of Smac demonstrated the specificity and utility of this assay. We have screened the National Cancer Institute "Training Set" of 230 compounds, with well-defined biological actions, and the "Diversity Set" of 2000 chemically diverse structures for compounds which significantly reduced fluorescence polarization. Highly fluorescing or fluorescence-quenching compounds (false positives) were distinguished from those which interfered with Smac peptide binding to the XIAP-BIR3 in a dose-dependent manner (true positives). This robust assay offers potential for high-throughput screening discovery of novel compounds simulating the action of Smac/DIABLO.
Collapse
Affiliation(s)
- Constance J Glover
- Developmental Therapeutics Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Banks P, Harvey M. Considerations for using fluorescence polarization in the screening of G protein-coupled receptors. JOURNAL OF BIOMOLECULAR SCREENING 2002; 7:111-7. [PMID: 12006109 DOI: 10.1177/108705710200700203] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Fluorescence polarization must be classified as a unique detection method relative to other intensity-based methods because both bound and unbound tracer is measured. Other fluorescence techniques require either physical removal of unbound tracer or a means for distinguishing only bound tracer. The presence of unbound tracer in the detection volume has profound consequences on how assay performance is gauged. The intent here is to provide tools for accurate assay performance assessment and to discuss some of the practical considerations necessary for understanding the advantages and limitations of the technology. An emphasis is placed on applications using G protein-coupled receptors.
Collapse
Affiliation(s)
- Peter Banks
- PerkinElmer Life Sciences, Montreal, Quebec, Canada.
| | | |
Collapse
|
15
|
Allen M, Hall D, Collins B, Moore K. A homogeneous high throughput nonradioactive method for measurement of functional activity of Gs-coupled receptors in membranes. JOURNAL OF BIOMOLECULAR SCREENING 2002; 7:35-44. [PMID: 11897054 DOI: 10.1177/108705710200700106] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A method is described for measuring the activity of G(s)-coupled receptors in a nonradioactive homogeneous membrane-based assay. This method has several major advantages over currently used methods for measuring functional activity of G(s)-coupled receptors. The assay is high throughput (>150,000 data points/day using a single reader). Dimethyl sulfoxide tolerance is high ( approximately 10%). Compared to complex cell-based assays, there is limited potential for nonspecific compound action. This resulted in low compound hit rates in robustness screening, where hit rates from a simulated screen were 1.0% (antagonist screen) and 0.1% (agonist screen). No continuous cell culture is required for the assay, reducing cell culture overheads and allowing the screen to run every day. Automation is simple and requires no temperature- or humidity-controlled incubation. No radioactivity is required. The method relies on measurement of cyclic AMP (cAMP) generation by fluorescence polarization assay using commercially available reagents. Membranes (1-2 microg protein per well, containing anti-cAMP antibody) are transferred to 384-well plates containing 1 microl test compound. For antagonist screens, agonist is added 15 min later. After 30 min incubation at room temperature, one further assay reagent (fluorescein-cAMP in a buffer containing detergent) is added. The signal may be read after 1 h and is stable for greater than 12 h. Typical Z' for the assay is approximately 0.5.
Collapse
Affiliation(s)
- Michael Allen
- Systems Research, GlaxoSmithKline, Stevenage, Herts, UK.
| | | | | | | |
Collapse
|