Adenosine receptor (A1, A2A, A2B, A3) (ADORA)

Adenosine receptors, also known as P1 receptors, are a class of G protein-coupled receptors (GPCRs) that mediate the physiological effects of adenosine across various tissues [1]. The family consists of four subtypes: A1, A2A, A2B, and A3, which differ in their G-protein coupling and affinity for adenosine [1, 4]. A1 and A3 receptors typically couple to Gi/o proteins to inhibit adenylyl cyclase, while A2A and A2B couple to Gs proteins to stimulate it [1]. These receptors play critical roles in the central nervous system, cardiovascular system, and immune regulation, influencing processes such as sleep, heart rate, and inflammatory responses [2, 4]. Caffeine acts as a non-selective antagonist of these receptors, particularly A1 and A2A, which accounts for its stimulant effects by blocking the sedative actions of endogenous adenosine [3]. Therapeutically, adenosine receptors are targeted for conditions ranging from supraventricular tachycardia and Parkinson's disease to cancer and chronic inflammation [4]. Understanding the subtype-specific distribution and signaling is essential for developing selective drugs with minimized side effects [1, 4]. Sources: [1] Fredholm BB, et al. (2011) Pharmacol Rev; [2] StatPearls (2023) Adenosine; [3] Ribeiro JA, et al. (2002) J Alzheimers Dis; [4] Chen JF, et al. (2013) Nat Rev Drug Discov.

Other names

P1 receptorsAdenosine A1 receptorAdenosine A2A receptorAdenosine A2B receptorAdenosine A3 receptorADORA1ADORA2AADORA2BADORA3

Antagonism of adenosine receptors (primarily A1 and A2A) to block the inhibitory effects of endogenous adenosine, or agonism to induce physiological responses like vasodilation or heart rate reduction.