GPCR Fluorescent Ligand Products
GPCRs are membrane proteins that convert an extracellular stimulus into an intracellular reaction. They have seven transmembrane spanning domains, an extracellular N-terminus, and an intracellular C-terminus. They make up the biggest family of proteins targeted by clinically used medications, making up about 4% of the human genome that codes for proteins. Roughly 30% of all medications target a GPCR. Nonetheless, just 30% of non-olfactory GPCRs and roughly 16% of all GPCRs in the human genome are represented by these targeted GPCRs, leaving plenty of room for additional drug development. Creative Biolabs offers GPCR fluorescent ligands which are made up of a fluorescent molecule attached chemically to either an agonist or an antagonist.
Fig.1 Fluorescent environment-sensitive GPCR ligands. (Hanser, 2021)
Applications of GPCR Fluorescent Ligands
Finding a new drug-like molecule for a GPCR requires several preliminary procedures, one of which is figuring out the molecule's affinity for the target receptor. The effects of varying test compound concentrations on the binding of a labeled molecule are assessed in equilibrium competition ligand-binding assays, which are frequently used to estimate the affinities of unlabelled compounds. The same basic concepts apply to competition binding assays whether a ligand is radiolabelled or fluorescently labeled; the end goal is to calculate the amount of ligand bound. The amount of fluorescent ligand bound can be determined by a variety of methods. The two main types of methods that employ fluorescent ligands are direct fluorescence measurement and indirect fluorescence measurement via resonance energy transfer. Our GPCR fluorescent ligands can be used in:
- Fluorescence polarization
- Homogeneous Time Resolved Fluorescence
- High-content analysis
- Fluorescence Microscopy
- Flow cytometry
Fig.2 Measuring ligand binding using fluorescence-based approaches. (Soave, 2020)
Cases of GPCR Fluorescent Ligands
- Fuorescence-based technologies have become an intriguing alternative to explore ligand affinity in recent years. In FRET ligand binding assays at D2R, a fluorescently labeled agonist (2-(N-phenethyl-N-propyl) amino-5-hydroxytetralin scaffold, PPHT-red) was used. Besides the agonistic PPHT derivatives, different fluorescent ligands incorporating an antagonistic NAPS scaffold have also been identified. For example, microscopic studies of ligand binding at D3R have been conducted using a Cy3B-labeled NAPS derivative.
- GPCR pharmacology can also be studied by utilizing fluorescent ligands to investigate binding kinetics. The leucine-rich repeats at the N-terminus of the relaxin family peptide receptor 1 (RXFP1) interact with the endogenous ligand relaxin. An extracellular linker region has additional contact sites that have been discovered. Researchers employed a relaxin that was fluorescently labeled in a kinetic test to better understand how these areas interact with one another when the ligand is bound.
References
- Hanser, F.; et al. Nile Red-based GPCR ligands as ultrasensitive probes of the local lipid microenvironment of the receptor. ACS Chemical Biology. 2021, 16(4): 651-660.
- Soave, M.; et al. Fluorescent ligands: Bringing light to emerging GPCR paradigms. British Journal of Pharmacology. 2020, 177(5): 978-991.
