“The mechanism of action of cannabidiol (CBD), the main non-psychotropic component of Cannabis sativa L., is not completely understood. First assumed that the compound was acting via cannabinoid CB₂ receptors (CB₂Rs) it is now suggested that it interacts with non-cannabinoid G-protein-coupled receptors (GPCRs); however, CBD does not bind with high affinity to the orthosteric site of any GPCR.

To search for alternative explanations, we tested CBD as a potential allosteric ligand of CB₂R. Radioligand and non-radioactive homogeneous binding, intracellular cAMP determination and ERK1/2 phosphorylation assays were undertaken in heterologous systems expressing the human version of CB₂R.

These results may help to understand CBD mode of action and may serve to revisit its therapeutic possibilities.”

https://www.ncbi.nlm.nih.gov/pubmed/29109685

https://www.frontiersin.org/articles/10.3389/fphar.2017.00744/full