Fig. 4

Electrostatic interactions at the interface of MANF and BiP NBD. a Detailed view of the NBD–SAP interface highlighting R133, K138, and E153 of SAP (gold) that form ionic interactions and hydrogen bonds with indicated residues of BiP NBD subdomains IIa (blue) and Ia (gray). b Detailed view of the NBD–MANF complex structure colored as in (a). c Bio-layer interferometry (BLI) trace (association and dissociation phases) of the binding signal arising from the interaction of streptavidin BLI biosensors loaded with biotinylated BiP NBD and exposed to MANF (at 10 µM) in buffer solutions containing the indicated salt concentrations. Shown is a representative of three experiments. d Plot of the binding signal at equilibrium arising from the interaction of streptavidin BLI biosensors loaded with biotinylated BiP NBD and the indicated concentrations of wild-type MANF or its mutants. Data points represent mean values and SD bars from three independent experiments. The K_{1/2 max} and R² values as well as fit lines are provided for the wild-type MANF and the R23A and K138A mutants. K_{1/2 max} and R² values are not provided for the R133E and E153A mutants as these gave rise to binding signals that were too weak to fit to a saturable one-site binding model. Source data are provided as a Source Data file