Cannabinoid receptor
CB 1 affinity ( K i ) Efficacy towards CB 1 CB 2 affinity ( K i ) Efficacy towards CB 2 Type
Anandamide 78nM Partial agonist 370nM ? Endogenous
N-Arachidonoyl dopamine ? Agonist ? ? Endogenous
2-Arachidonoylglycerol ? Full agonist ? ? Endogenous
2-Arachidonyl glyceryl ether 21 nM Full agonist 480nM Full agonist Endogenous
Δ-9-Tetrahydrocannabinol 10nM Partial agonist 24nM Partial agonist Phytogenic
EGCG 33.6μM Agonist > 50μM ? Phytogenic
Yangonin 0.72 μM ? > 10 μM ? Phytogenic
AM-1221 52.3nM Agonist 0.28nM Agonist Synthetic
AM-1235 1.5nM Agonist 20.4nM Agonist Synthetic
AM-2232 0.28nM Agonist 1.48nM Agonist Synthetic
UR-144 150nM Full agonist 1.8nM Full agonist Synthetic
JWH-007 9.0nM Agonist 2.94nM Agonist Synthetic
JWH-015 383nM Agonist 13.8nM Agonist Synthetic
JWH-018 9.00 ± 5.00 nM Full agonist 2.94 ± 2.65 nM Full agonist Synthetic
Ligands -- Binding affinity and selectivity of cannabinoid ligands
Cannabinoid receptors, located throughout the body, are part of the endocannabinoid system, which is involved in a variety of physiological processes including appetite, pain-sensation, mood, and memory. Cannabinoid receptors are of a class of cell membrane receptors in the G protein-coupled receptor superfamily. As is typical of G protein-coupled receptors, the cannabinoid receptors contain seven transmembrane spanning domains. Cannabinoid receptors are activated by three major groups of ligands: endocannabinoids, produced by the mammillary body; plant cannabinoids (such as cannabidiol, produced by the cannabis plant); and synthetic cannabinoids (such as HU-210). All of the endocannabinoids and phytocannabinoids (plant based cannabinoids) are lipophilic, such as fat soluble compounds. There are currently two known subtypes of cannabinoid receptors, termed CB and CB. The CB receptor is expressed mainly in the brain (central nervous system or CNS), but also in the lungs, liver and kidneys. The CB receptor is expressed mainly in the immune system and in hematopoietic cells, however further research has found the existence of these receptors in parts of the brain as well. Mounting evidence suggests that there are novel cannabinoid receptors that is, non-CB and non-CB, which are expressed in endothelial cells and in the CNS. In 2007, the binding of several cannabinoids to the G protein-coupled receptor GPR55 in the brain was described. The protein sequences of CB and CB receptors are about 44% similar. When only the transmembrane regions of the receptors are considered, amino acid similarity between the two receptor subtypes is approximately 68%.