The global market for G-Protein Coupled Receptors (GPCRs) is projected to reach US$3.8 billion by the year 2027, trailing a post COVID-19 CAGR of 5.7% over the analysis period 2020 through 2027. Global healthcare systems continue to be inadequate, leaving a lot to be desired. Over 50% of the world's population lacks access to essential health services. Low quality healthcare is increasing the burden of disease, morality in addition to pushing up medical costs. COVID-19 is bringing transformational change in the way the world is beginning to prioritize healthcare and drug development. Post pandemic, there will be robust need and demand for the development of new and affordable medicines. The scenario brings good news for G-Protein Coupled Receptors (GPCRs), given the fact that over 45% of all drugs work by targeting GPCRs. The most intensively studied class of drug targets, GPCRs represent signal-transducing molecules that transmit signals to cells. They play a key role in converting extracellular stimulus into intracellular responses, and are therefore responsible for all physiological processes. Also referred to as heptahelical receptor or seven-trans membrane receptor, GPCRs consist of a large family of trans-membrane receptor proteins that play a vital role in signal transduction pathways in various physiological processes. Thus, by targeting GPCRs, a number of cellular functions can be controlled. GPCR-based drugs represent around 40% of the total approved drugs available in the market.

In addition, GPCRs that were previously untargeted are fast becoming validated targets, with an average of 3.5 receptors each year. G protein-coupled receptors (GPCRs) are membrane proteins that are located on the surface of a cell. Human genome comprises of around 30,000 genes, of which around 10% (3,000) genes are found to be drug gable targets. Out of the 3,000 genes, GPCRs are encoded by approximately 800-1,000 genes in the human body, and thus, comprise of the largest cell-surface receptor family. Furthermore, in the GPCR superfamily only around 360 receptors are non-chemosensory/ non-sensory and thus, are identified as validated drug targets, while the remaining are sensory receptors. GPCRs are present only in eukaryotes such as choanoflagellates and yeast, as well as in animals. GPCRs are also called 7TM receptors, 7trans-membrane domain receptors, serpentine receptors, and G-protein linked receptors (GPLR), and heptahelical receptors. The transmembrane domains are linked by 3 extracellular and 3 intracellular loops. The most important feature of GPCRs is that they are expressed at the surface of the cell, and communicate certain specific aspects of the extra-cellular environment to the intra-cellular environment.

Drugs targeting GPCR have superior therapeutic benefits, as they are more active at cell surface receptors. The importance of GPCRs can be put into perspective by the fact that approximately 35% to 40% of all pharmaceutical drugs in the marketplace target G-protein coupled receptors, making it one of the most vital classes of proteins in the genome. G protein?coupled receptors (GPCRs) are important drug targets with about 35% of FDA approved drugs targeting these receptors. GPCRs stimulate cellular responses and signal transduction inside the cell, upon sensing molecules outside. GPCR respond to various agonists, including proteins, neurotransmitters, hormones, amines, and photon. Some of the agonists attach themselves to receptor's extra cellular loop, while others penetrate in the trans-membrane region. Upon activation, a conformational change is induced in the receptor, which in turn activates GPCRs and subsequently biochemical signals are transmitted in the cell. Over the past two decades, there has been much research on understanding working of the receptors at the molecular level. There are also many studies ongoing for developing structure based GPCR drug designing, based on discoveries that various ligands are able to bind to same receptor but stimulate association of other effector proteins to varying extents. Such concept of biased agonism as well as functional selectivity have opened up major possibilities for development of more effective drugs with more desired therapeutic impacts, all while preventing harmful side-effects. Already, there have been many illustrations of how such biased GPCR ligands could prove to be useful in treating various diseases. Nonetheless, there is still much to be learnt about the various mechanisms that govern functional selectivity and ligand bias. Growth is forecast to be primarily driven by the increasing interest in GPCR drug targets, superior understanding of GPCR membrane structures, identification, and crystallization of newer structures, development of more powerful and efficient GPCR screening tools and technologies, and successful extrapolation of known structural information to other GPCRs of therapeutic interest. More than 360 endoGPCRs represent the largest and most therapeutically targeted class of membrane receptors in humans. However only 30-40% that have well-defined biological ligands are drug gable at present. The remaining 60-70% hold significant potential for development of new drug therapeutics.