CB2 R is a 7TM protein that belongs to the family of G protein-coupled receptors, class A. CB2 R is expressed in the periphery, notably by hematopoietic cells, in contrast to CB1 R, which is expressed predominantly in the central nervous system and gut. CB2 R on lymphocytes and macrophages binds cannabinoids and modulates cytokine secretion. With the exception of their divergent C-terminal tails, human CB2 R shares 82% amino acid sequence identity with mouse and rat CB2 R.