Making Transfluor 
Atto Pathway 
Transfluor Assay from Atto Gentaur

Norak Biosciences, Inc. is a private biotechnology company based in Research Triangle Park, NC, utilizing its proprietary Transfluor® technology to become a world leader in the discovery and development of drugs that regulate G protein-coupled receptors (GPCRs).

We invite you to tour our website to learn more about Norak Biosciences, our technology and our discovery efforts.

Norak News...

Norak Biosciences Licenses Transfluor® to DCB [read more]

Norak Biosciences Acquires Broad Rights from European Transfluor® Patent [read more]

Norak Biosciences Delivers on an Agreement with Sumitomo Pharmaceuticals Co., Ltd. [read more].

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Unique ransfluor® Presentations


Hoffman - La Roche Presentation: High-Content Analysis Conference

Merck Presentation: High-Content Analysis Conference

Norak Presentation: High-Throughput Screening for Drug Discovery Conference


AstraZeneca Presentation: Society for Biomolecular Screening 2003

Merck Presentation: Society for Biomolecular Screening 2003

Norak Presentation: Assays & Cellular Targets (ACT) Conference

Norak Presentation: Drug Discovery Technologies 2003 Conference

Norak Presentation: MipTec 2003 Conference

Hoffman - La Roche Presentation: Society for Biomolecular Screening 2003

Transfluor® Posters

Comparison of Compound Characterization with Transfluor® and AlphaScreen™

Development, Conduct and Results of Two High Throughput Screens Using Transfluor® Technology

Microtiter Plate Evaluation for Use with Cell-Based, High Content Imaging Systems

Multiplexing of Transfluor® Technology to Detect Responses Gs-,Gi- and Gq-coupled Receptors in the Same Well

Screening Orphan GPCRs in Stable Cell Lines with Transfluor® Technology

Transfluor® Technology: A Universal High-Content Screening Assay for G Protein-Coupled Receptors

Other Transfluor® Information

Arrestin Translocation Cartoon

Atto Bioscience Presentation: Norak's Transfluor® GPCR Assay on Atto Bioscience's Pathway HT™

Cellomics Application Note: GPCR Signaling BioApplication

Cellomics Poster: Ranking of ß2 Adrenergic Receptor Agonists and Antagonists Using a Cell-Based GPCR Signaling BioApplication

Cellomics™ Application Note: Transfluor® Technology for High-Content Screening of GPCRs

Cellomics™ Application Note: Analysis of GPCRs with the Spot Detector BioApplication and Transfluor® Technology

iCyte™/Transfluor® Application Note

iCyte™/Transfluor® Application Note (Japanese version by Olympus)

Olympus Presentation: Transfluor® Assay by iCyte™ Imaging Cytometer

Publications List: ß-arrestin Translocation

Q3DM Application Note: Analysis of GPCR Activity on the EIDAQ™ 100 High Throughput Microscopy System

Q3DM Application Note: Norak Transfluor® GPCR Assay – Q3DM EIDAQ™ 100 HTM Analysis

Transfluor I

Transfluor II

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Today, there are nearly 200 GPCRs whose ligands and function are known representing a wide variety of physiologies. Due to the overwhelming variety of physiologies regulated, GPCRs have been the richest targets in history for drug discovery. It is estimated that nearly 60% of all prescription drugs on the market owe their activity in whole or in part to GPCRs.

While some natural ligands of GPCR have important therapeutic value (e.g., epinephrine, dopamine and adenosine), most GPCR drugs are synthetic ligands or derivatives that bind and either activate or block the receptor, so-called agonists and antagonists, respectively. Many if these compounds have pure stimulatory or inhibitory properties, while others elicit mixed activity including partial agonists or antagonists, inverse agonists, and allosteric modulators.

Despite a wide variety of marketed GPCR-based drugs, the functionally known receptors remain important targets for new and improved drugs. In addition, approximately 150 additional human GPCRs are believed to be important in disease states but their natural ligands have yet to be identified. These receptors are called orphan GPCRs. Orphan GPCRs present great opportunities for the discovery of new medicine to satisfy unmet medical conditions.

Norak Biosciences is utilizing its proprietary Transfluor® technology to advance the discovery of GPCR-based drugs. Transfluor, an advanced, cell-based, compound screening method universally applicable to known and orphan GPCRs, represents a breakthrough technology that bridges high throughput screening and high content screening. With Transfluor, Norak and its partners have successfully identified small molecule compounds that modulate various human GPCR in cell-based assays.

Transfluor® is an advanced, cell-based screening technology applicable to all known and orphan GPCRs. Transfluor® has been successfully validated on over 90 GPCRs, and works across all GPCR classes (Class I, II, III), regardless of interacting G-protein (Gs, Gi/o and Gq/11). Transfluor® eliminates the need for multiple GPCR assay platforms.

The following dose-response curves, representing receptors coupled to different G proteins, illustrate the broad utility of the Transfluor® technology.

The Transfluor technology monitors receptor activity by detecting movement of ß arrestin-GFP in the cell. A partial listing of GPCRs that have been shown to translocate ß arrestin-GFP is shown below.

  1. Gs
  2. Gi/o
  3. Gq/11
  4. A2a adenosine
  5. A2b adenosine
  6. ß1-adrenergic
  7. ß2-adrenergic
  8. CRF1 corticotropin releasing factor
  9. D1 dopamine
  10. D5 dopamine
  11. FSH follicle-stimulating hormone
  12. Glucagon
  13. LH luteinizing hormone
  14. PTH1 parathyroid hormone
E2 prostaglandin
E4 prostaglandin
VIP1 vasoactive intestinal peptide
V2 vasopressin
alpha 2a-adrenergic
alpha 2b-adrenergic
alpha 2c-adrenergic
A1 adenosine
A3 adenosine
C5a anaphylatoxin
CCR5 chemokine
CXCR1 chemokine
CXCR2 chemokine
CXCR4 chemokine
D2 dopamine
D3 dopamine
D4 dopamine
Edg1 endothelial diff. gene
Edg2 endothelial diff. gene
Edg3 endothelial diff. gene
Edg5 endothelial diff. gene
5HT1A hydroxytryptamine
MCH1 melanin conc. hormone
M2Ach muscarinic acetylcholine
E3 prostaglandin
N-formyl peptide
Neuropeptide FF
alpha 1b-adrenergic
AT1A angiotensin II
CCK-A cholecystokinin
CCK-B cholecystokinin
Cytomegalovirus US28
ETA endothelin
GnRH (type2) gonadotropin releasing hormone
5HT2A hydroxytryptamine
5HT2C hydroxytryptamine
m1ACh muscarinic acetylcholine
mGluR1 metabotropic glutamate
NK1 neurokinin
NK3 neurokinin
NT1 neurotensin
PAR2 proteinase-activated
Platelet-activating factor
TRHR-1 thyrotropin releasing hormone
TRHR-2 thyrotropin releasing hormone

12 Drosophila GPCRs
Fz4 frizzled receptor
TßRIII transforming growth factor-ß


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