Why is it important to identify a new CB receptor? Does it not mean that discovering a new cannabinoid receptor not tell us that we still do not know much about the endocannabinoid system? The CB1 and CB2 receptors show many similar characteristics, but GPR55 has very little in common with the other two receptors. The GPR55 molecule shares less than 15 % of its amino acid identity with either one of them.