Background：The cannabinoid delta-9-tetrahydrocannabinol is the principal psychoactive ingredient of marijuana. The proteins encoded by this gene and the cannabinoid receptor 1 （brain） （CNR1） gene have the characteristics of a guanine nucleotide-binding protein （G-protein）-coupled receptor for cannabinoids. They inhibit adenylate cyclase activity in a dose-dependent, stereoselective, and pertussis toxin-sensitive manner. These proteins have been found to be involved in the cannabinoid-induced CNS effects （including alterations in mood and cognition） experienced by users of marijuana. The cannabinoid receptors are members of family 1 of the G-protein-coupled receptors.
