Serine 3.39 and isoleucine 4.60 are key sites for 5-HT2AR-mediated Gs signaling

Certain amino acid sites of 5-HT_2AR play crucial roles in interacting with various G proteins. Hallucinogens and non-hallucinogens both act on 5-HT_2AR but mediate different pharmacological effects, possibly due to the coupling of different G proteins. Therefore, this study identified the binding sites of hallucinogens and non-hallucinogens with 5-HT_2AR through molecular docking. We conducted site mutation to examine the impact of these sites on G proteins, in order to find out the sites that can distinguish the pharmacological effects of hallucinogens and non-hallucinogens. Our results indicate that I4.60A and S3.39A did not affect the ability of hallucinogens to activate G_q signaling, but significantly reduced G_s signaling activation by hallucinogens. These results suggest that S3.39 and I4.60 are important for the activation of G_s signaling by hallucinogens.