Fig. 4: Cryo-EM structures of LGR4-NB18 complexes.
From: Distinct structural mechanisms of LGR4 modulation by Norrin and RSPOs in Wnt/β-catenin signaling
a Binding affinity measurements between LGR4 and NB18 using biolayer interferometry. b, c Cryo-EM structure of the LGR4-NB18 complex, showing the Cryo-EM map (b) and corresponding atomic model (c). LGR4 is displayed in light green, NB18 in salmon, with the nanobody portion of MB52 in gray (remaining segments are omitted for clarity). d Close-up view of the LGR4-NB18 binding interface, highlighting key residues involved in specific interactions. e, f Superimposition of LGR4 from the LGR4-NB18 complex with LGR4 from the LGR4-RSPO2-ZNRF3 and LGR4-Norrin complexes. LGR4 is shown in light green, with Norrin in magenta and RSPO2 in blue; non-essential segments are omitted for clarity. g TOPFlash reporter assay in HEK293T cells demonstrate that NB18 (5 μM) inhibits LGR4-mediated Wnt signaling activity upon RSPO2-Fc stimulation. h, i Dose-dependent inhibition of Wnt signaling activity by NB18 in response to Norrin-Fc (75 nM) (h) and RSPO2-Fc (0.2 nM) (i) stimulation, as measured by TOPFlash reporter assay in HEK293T cells. NB18 was tested in a concentration-dependent manner to generate full dose-response curves. g–i: n = 3, all error bars represent the S.E.M. Source data are provided as a Source Data file.
