G protein-coupled receptors (GPCRs)
G protein-coupled receptors (GPCRs) are a large family of cell membrane proteins that play a crucial role in signal transduction. They are involved in many different physiological functions and are targeted by a large percentage of currently marketed drugs, including those used to treat conditions such as hypertension, asthma, schizophrenia, and Parkinson's disease.The basic structure of a GPCR includes seven transmembrane alpha helices, an extracellular N terminus, and an intracellular C terminus. They are called "G protein-coupled" because when they bind to their ligand (such as a hormone or neurotransmitter) on the outside of the cell, they activate an intracellular G protein. This G protein then triggers a series of downstream events inside the cell, leading to the cell's response to the original signal.There are several different types of G proteins, and the specific G protein that a GPCR interacts with determines the downstream effects. For example, some G proteins activate enzymes that increase the production of cyclic AMP (cAMP), a common second messenger, while others inhibit this process. Other G proteins activate different signaling pathways altogether.The GPCR family is incredibly diverse, with receptors for a wide variety of signals. These include light-sensitive receptors in the retina, smell receptors in the nose, and a wide range of hormone and neurotransmitter receptors throughout the body. Because of their involvement in so many different physiological processes, they are a major focus of pharmaceutical research.
- 5-Hydroxytryptamine receptors
- Acetylcholine receptors (muscarinic)
- Adenosine receptors
- Adhesion Class GPCRs
- Adrenoceptors
- Angiotensin receptors
- Apelin receptor
- Bile acid receptor
- Bombesin receptors
- Bradykinin receptors
- Calcitonin receptors
- Calcium-sensing receptor
- Cannabinoid receptors
- Chemerin receptors
- Chemokine receptors
- Cholecystokinin receptors
- Class Frizzled GPCRs
- Complement peptide receptors
- Corticotropin-releasing factor receptors
- Dopamine receptors
- Endothelin receptors
- G protein-coupled estrogen receptor
- Formylpeptide receptors
- Free fatty acid receptors
- GABABreceptors
- Galanin receptors
- Ghrelin receptor
- Glucagon receptor family
- Glycoprotein hormone receptors
- Gonadotrophin-releasing hormone receptors
- GPR18, GPR55 and GPR119
- Histamine receptors
- Hydroxycarboxylic acid receptors
- Kisspeptin receptor
- Leukotriene receptors
- Lysophospholipid (LPA) receptors
- Lysophospholipid (S1P) receptors
- Melanin-concentrating hormone receptors
- Melanocortin receptors
- Melatonin receptors
- Metabotropic glutamate receptors
- Motilin receptor
- Neuromedin U receptors
- Neuropeptide FF/neuropeptide AF receptors
- Neuropeptide S receptor
- Neuropeptide W/neuropeptide B receptors
- Neuropeptide Y receptors
- Neurotensin receptors
- Opioid receptors
- Orexin receptors
- Oxoglutarate receptor
- P2Y receptors
- Parathyroid hormone receptors
- Platelet-activating factor receptor
- Prokineticin receptors
- Prolactin-releasing peptide receptor
- Prostanoid receptors
- Proteinase-activated receptors
- QRFP receptor
- Relaxin family peptide receptors
- Somatostatin receptors
- Succinate receptor
- Tachykinin receptors
- Thyrotropin-releasing hormone receptors
- Trace amine receptor
- Urotensin receptor
- Vasopressin and oxytocin receptors
- VIP and PACAP receptors