Fig. 3. Opioid dimerization. Figure depicts opioid receptor homodimers and opioid receptor heterodimers (A ); heterodimers between opioid receptors and other G-protein–coupled receptors (B ); protein–protein interactions involved in opioid receptor signal transduction (C ). βγ = G protein β-γ subunit; μ = μ opioid receptor; δ = δ opioid receptor; CB1 = cannabinoid receptor type 1; GPCR = G protein coupled receptors; κ = κ opioid receptor; ORL-1 = opioid receptor like-1; arrow = movement; T lines = blockade.