Here we report single-particle cryo-EM structures of human S1P receptor 1 (S1P1) and heterotrimeric Gi complexes formed with bound S1P or the multiple sclerosis (MS) treatment drug Siponimod, as well as human LPA receptor 1 (LPA1) and Gi complexes in the presence of LPA. The gene discussed is GNAI1; the disease is myeloid sarcoma.