G
Protein-coupled
Receptors
(GPCRs),
also
konwn
as
7-
transmembrane receptors (7-TM receptors), are the largest family of membrane receptors with nearly 1,000 presented in the human genome. They are found only in eukaryotes (e.g., yeast, plants and animals), and can be activated by neurotransmitters, hormones, pheromones, odors, etc. Being involved in diseases such as cancers, immunological disorders, metabolic disorders, cardiovascular diseases, and mental illnesses, GPCRs are an important drug targets and estimated to be targets of 50% of drugs currently on the market. There are two signaling transduction pathways involving GPCRs: the cAMP signaling pathway and the phosphatidylinositol signaling pathway. The mechanism of the signaling pathways includes the activation of GPCR by an external signal in the form of a ligand, which creates a conformational change in the receptor, thus, causing activation of a G protein (guanine nucleotide-binding proteins).
Class
Receptor Family Name
Type of Ligand
Class A (or 1)
Rhodopsin-like receptors
Hormone, Neuropeptide, Neurotransmitter, and Light
Class B (or 2)
Secretin family receptors
Hormone (e.g., secretin and glucagon)
Class C (or 3)
Metabotropic glutamate/pheromone receptors
Glutamate
Class D (or 4)
Fungal mating pheromone receptors
Mating factors
Class E (or 5)
Cyclic AMP receptors
cAMP
Class F (or 6)
Frizzled/Smoothened receptors
Wnt proteins/Hedgehog (Hh)
One of the great features of GPCRs is that they are druggable. Despite that, only a small percentage of the known and verified GPCRs have been targeted for therapeutics. Hence, there remains enormous scope for researchers to delineate the numerous roles of GPCRs in basic physiology and pathophysiology, and to thereby understand and develop new treatments for disease.
06
02 GPCR Stable Cell Line