Fig. 3: Recognition of IgM by AIM.

a Model showing the Fcμ/J/AIM interfaces in the complex (lower region of model in Fig. 1b). b Interactions between the stabilised β-hairpin 2 and Cμ3 and Cμ4 domains in subunit Fcμ5 (black dashed box in (a)). c Disulfide bond, potential salt bridges (blue dashed lines) and van der Waals contact (red dashed lines) between the two SRCR domains in AIM and IgM (red dashed box in (a)). d Calcium binding sites (Ca²⁺-1 and Ca²⁺−2) on SRCR3 at the interface between AIM and J chain (purple dashed box in (a)). e Binding of AIM (WT and mutants) to IgM at different calcium ion concentrations in an ELISA-based assay. Error bars indicate the s.e.m. for three technical replicates. Data is representative of three biological replicates. Source data are provided as a Source Data file.