Heterotrimeric G protein-coupled receptor for endocannabinoid 2-arachidonoylglycerol mediating inhibition of adenylate cyclase. May function in inflammatory response, nociceptive transmission and bone homeostasis. Localizes to apical dendrite of pyramidal neurons. Preferentially expressed in cells of the immune system with higher expression in B-cells and NK cells (at protein level). Expressed in skin in suprabasal layers and hair follicles (at protein level). Highly expressed in tonsil and to a lower extent in spleen, peripheral blood mononuclear cells, and thymus. PubMed:14657172 could not detect expression in normal brain. Expressed in brain by perivascular microglial cells and dorsal root ganglion sensory neurons (at protein level). Two isoforms are produced by alternative promoter usage and differ only in the 5' UTR: isoform CB2A is observed predominantly in testis with some expression in brain, while isoform CB2B is predominant in spleen and leukocytes. In macrophages, down-regulated by endocannabinoid anandamide/AEA. Constitutively phosphorylated on Ser-352; phosphorylation increases cell internalization and desensitizes the receptor. Belongs to the G-protein coupled receptor 1 family.