The prototypical hallucinogen LSD acts via serotonin receptors， and here we describe the crystal structure?of LSD in complex with the human serotonin receptor 5-HT. The complex reveals conformational rearrangements to accommodate LSD， providing a structural explanation for the conformational selectivity of LSD's key diethylamide moiety. LSD dissociates exceptionally slow from both 5-HTR and 5-HTR-a major target for its psychoactivity. Molecular dynamics (MD) simulations suggest that LSD's slow binding kinetics may be due to a "lid" formed by extracellular loop 2 (EL2) at the entrance to the binding pocket. A mutation predicted to increase the mobility of this lid greatly accelerates LSD's binding kinetics a... More
The prototypical hallucinogen LSD acts via serotonin receptors， and here we describe the crystal structure?of LSD in complex with the human serotonin receptor 5-HT. The complex reveals conformational rearrangements to accommodate LSD， providing a structural explanation for the conformational selectivity of LSD's key diethylamide moiety. LSD dissociates exceptionally slow from both 5-HTR and 5-HTR-a major target for its psychoactivity. Molecular dynamics (MD) simulations suggest that LSD's slow binding kinetics may be due to a "lid" formed by extracellular loop 2 (EL2) at the entrance to the binding pocket. A mutation predicted to increase the mobility of this lid greatly accelerates LSD's binding kinetics and selectively dampens LSD-mediated β-arrestin2 recruitment. This study thus reveals an unexpected binding mode of LSD; illuminates key features of its kinetics， stereochemistry， and signaling; and provides a molecular explanation for LSD's actions at human serotonin receptors. PAPERCLIP.
