Structure of S1PR2-heterotrimeric G signaling complex.

Sphingosine-1-phosphate (S1P) regulates immune cell trafficking, angiogenesis, and vascular function via its five receptors. Inherited mutations in S1P receptor 2 (S1PR2) occur in individuals with hearing loss, and acquired mutations in S1PR2 and G occur in a malignant lymphoma. Here, we present the cryo-electron microscopy structure of S1P-bound S1PR2 coupled to the heterotrimeric G. Interaction between S1PR2 intracellular loop 2 (ICL2) and transmembrane helix 4 confines ICL2 to engage the α5 helix of G. Transforming growth factor-α shedding assays and cell migration assays support the key roles of the residues in S1PR2-G complex assembly. The structure illuminates the mechanism of receptor disruption by disease-associated mutations. Unexpectedly, we showed that FTY720-P, an agonist of the other four S1PRs, can trigger G activation via S1PR2. S1PR2 variant can increase the activity of G considerably with FTY720-P and S1P, thus revealing a basis for S1PR drug selectivity.