Signal transduction cascades, interaction with structure

Two cannabinoid (CB) receptors with about 40 % homology have been identified and cloned to date, namely CBi and CB2. These receptors belong to the superfamily of G-protein coupled membrane receptors [29] and consequently they show a typical heptahelical structure. Interaction with cannabinoid receptors stimulates a cascade of signal transduction pathways, including interaction with potassium and calcium channels (for CBi) and several kinases (e.g., MAP kinase). Since a number of cannabinoid-Uke effects persist in CB1/CB2 knockout mice, the existence of other cannabinoid receptors different from CBi and CB2 has been suggested (e.g., GPR55) [[30], [31]], but their effective role still awaits to be clearly defined. 

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