G-protein-coupled receptors for adenosine that regulate a variety of physiological functions including cardiac rate and contractility, smooth muscle tone, sedation, release of neurotransmitters, platelet function, lipolysis, renal function, and white blood cell function. A1 receptors are ubiquitously expressed in the central nervous system and in a range of peripheral tissues and agonists induce calcium release and a transient inositol 1,4,5-trisphosphate (IP3) increase. The A2A receptor is abundant in basal ganglia, vasculature, and platelets, and stimulates adenylyl cyclase. It is a major target of caffeine. The A2B receptor is actually a netrin-1 receptor that interacts with deleted in colorectal cancer and induces cAMP accumulation. The A3 receptor (319 aa) inhibits adenylyl cyclase.
Subjects: Medicine and Health — Chemistry.