The adenosine A1 receptor (ADORA1) is one member of the adenosine receptor group of GPCRs with adenosine as endogenous ligand. Activation of the adenosine A1 receptor by an agonist causes binding of Gi1/2/3 or Go protein. Binding of Gi1/2/3 causes an inhibition of adenylate cyclase and, therefore, a decrease in the cAMP concentration.
The adenosine A1 receptor appears throughout the entire body and plays an important role in sleep promotion by inhibiting wake-promoting cholinergic neurons in the basal forebrain. A1 receptors are also present in smooth muscle throughout the vascular system.
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