The cannabinoid receptor type 2, abbreviated as CB₂, is a G protein-coupled receptor from the cannabinoid receptor family that in humans is encoded by the CNR2 gene. It is closely related to the cannabinoid receptor type 1, which is largely responsible for the efficacy of endocannabinoid-mediated presynaptic-inhibition, the psychoactive properties of tetrahydrocannabinol, the active agent in marijuana, and other phytocannabinoids (natural cannabinoids). The principal endogenous ligand for the CB₂ receptor is 2-arachidonoylglycerol (2-AG).