“…Many class A GPCRs have been targeted using synthetic photoswitches ( Agnetta et al., 2017 ; Bahamonde et al., 2014 ; Broichhagen et al., 2015 ; Donthamsetti et al., 2017 ; Frank et al., 2017 ; Gómez-Santacana et al., 2018 ; Hauwert et al., 2018 ; Hüll et al., 2021 ; Morstein et al., 2020 ; Schönberger and Trauner, 2014 ; Westphal et al., 2017 ) among which, very recently, also β 1 -AR( Duran-Corbera et al., 2022 ) and β 2 -AR ( Duran-Corbera et al., 2020 ). On the other hand, irreversible molecules named caged compounds are produced by adding a photocleavable group to a known active molecule, which hampers the formation of the ligand-receptor complex, thus rendering the molecule inactive ( Tapia et al., 2021 ; Vickerman et al., 2021 ). On illumination, the photoprotecting group (PPG) is photolyzed and the active compound is locally and irreversibly released from the inactive precursor.…”