Fig. 5

Soluble nanobodies inhibit ligand binding and signaling of BCMA. a Superposition of the APRIL (PDB: 1XU2) and BAFF (PDB: 1OQD) complexes with our nanobody complexes based on BCMA. Neighboring APRIL chains that sandwich BCMA are colored pink and light pink, while BAFF chains are in aquamarine and pale cyan. b APRIL and BAFF interface compared to Nb1 and Nb2 epitopes on BCMA. Color coding is explained above the BCMA models. c Nanobodies inhibit APRIL-induced MM.1S proliferation. Data are represented as means and standard errors of the mean (SEM) of n = 3 replicates per group, the one-way analysis of variance (ANOVA) followed by Tukey’s multiple comparisons test was used to assess the differences among different groups. Data are represented as mean ± SEM. d Nb1 (2000nM; left), Nb2 (100 nM; middle), and NbT (10 nM; right) were probed for competitive binding against APRIL using SPR