Cryo-EM structure of cannabinoid receptor CB1-β-arrestincomplex

Dear Editor,G protein-coupled receptors(GPCRs)play a vital role in regulating almost every aspect of human physiology,making up more than one-third of marketed drug targets(Santos et al.,2017).GPCRs orchestrate their signalling through interactions with three distinct downstream protein families:G proteins,G protein-coupled receptor kinases(GRKs),and arrestins(Santos et al.,2017).While G protein-mediated signalling is initiated upon GPCR stimulation,activated GPCRs return to their basal levels through a GRK-and arrestin-regulated desensitization process(Santos et al.,2017).In addition to modulating receptor desensitization,β-arrestin also regulates downstream events that are distinct from classical G protein signalling(Ahn et al.,2020).