Fig. 1: Structural and functional analysis of JR14a binding to C3aR.
From: Structural insights into the agonist activity of the nonpeptide modulator JR14a on C3aR
a, b Dose-dependent inhibition of forskolin-induced cAMP by C3a and JR14a in C3aR/HEK293 (a) and THP-1 cells (b). c Activity of chemokines and C3aR ligands in inducing chemotaxis of neutrophils and monocytes. ***P < 0.001. Significance was determined with one-way ANOVA followed by Fisher’s LSD multiple-comparison test, compared with the no treatment group. d, e Cryo-EM density maps and cartoon presentation of the C3aR–BRIL–JR14a–BAG2 complex (d) and C3aR–JR14a–Gi complex (e). In the C3aR–BRIL–JR14a–BAG2 complex, C3aR is colored in turquoise, BRIL in tan, JR14a in orange, BAG2 heavy chain (HC) in purple and light chain (LC) in thistle. In the C3aR–JR14a–Gi complex, C3aR is shown in violet, JR14a in blue, G protein complex in khaki (Gα), green (Gβ) and rosy brown (Gγ), and scFv16 in silver. f Illustration of the chemical structure of JR14a highlighting its group composition. g, h Interactions between JR14a and C3aR. i Potencies of JR14a towards C3aR mutants in the binding pocket measured with calcium release assay. **P < 0.01, ***P < 0.001. NA not activated. Significance was determined with one-way ANOVA followed by Fisher’s LSD multiple-comparison test, compared with the wild type. j Comparison of the binding pockets in C3aR–JR14a and C3aR–C3a (PDB 8HK2) complexes. k Measurement of C5aR1 activation induced by C5a and JR14a with calcium release assay. l Overlay of C3aR–JR14a–Gi and C5aR–C5a–Gi (PDB 8HK5) structures. m Activation of C5aR-F44L/L92S/V286I by JR14a measured with calcium release assay; C5a serves as a positive control. All functional assay data are presented as means ± SEM from at least three independent experiments.
