GPCR Cell-Based Drug Screening In Vitro Assay Development Services
Creative Biolabs' ever-growing catalogue of GPCR assays can be used for high throughput screening, molecular pharmacology, and profiling with various readouts. We also developed a unique technology for orphan G protein-coupled receptors assay.
GPCRs are the most druggable targets because of their relevance in health and disease, as well as the possibility for therapeutic intervention employing small molecules as regulators. More than half of all currently available therapeutic medicines target these receptors, including more than a quarter of the top 100 best-selling medications, with annual earnings in the billions of dollars. The development of GPCR in vitro assays is still a prominent focus of drug discovery research around the world.
Fig.1 Schematic representation of major pathways activated by different G proteins. (Zhang & Xie, 2012)
Creative Biolabs has been working on developing cell-based functional assays to give more precise and comprehensive data on compounds that target GPCRs. We can offer GPCR cell-based drug screening in vitro assay development services, including:
GPCR Binding Assay
GPCR binding assays can be used to define the interaction between the receptor and its ligands in great detail, including the intrinsic affinity of ligands for the receptor, association/dissociation rates, and receptor density in tissues and cells. This type of assay can also provide both agonists and antagonists in the same experiment, but without determining whether the candidate molecule is an agonist, antagonist, or inverse agonist. The lack of labeled ligands severely limits the applicability of this test. For GPCR deorphanization, it is practically ineffective.
GPCR Functional Assay
Further analysis of the biological responses to the molecule after binding will help to complete the picture of the compound's overall properties. GPCRs change their conformation and activate linked G proteins in response to ligand binding, which increase second messenger synthesis via downstream effectors. On the other hand, GRKs phosphorylate agonist activated GPCRs on specific serine and threonine residues, and GRK-phosphorylated GPCRs bring cytosolic β-arrestins to the cell membrane. G-protein dependent or G-protein independent functional assays can be measured using the corresponding assays.
Ideal Assay for GPCR Drug Screening
GPCR drug screening assays should be simple, non-radioactive, durable, homogeneous, and easily adaptable to a microtiter plate format for robotic automation. Because GPCR signaling is made up of a series of spatial and temporal events, deciding whether to evaluate a proximal or distal signaling step after GPCR activation is also critical. Biased signaling, which happens when certain agonists have higher efficacy in activating one pathway than others, is another crucial element to consider when developing functional screens. If a functional test for screening chemical libraries only captures one signaling mechanism, potentially helpful compounds may be overlooked if the medicine has biased action. As a result, multiplexing of signaling channels or assays that represent an overall cellular response could be utilized to alleviate these issues.
Reference
- Zhang, R., Xie, X. Tools for GPCR drug discovery. Acta Pharmacologica Sinica. 2012; 33(3): 372-384.
