Figure 1.

XL-MS analysis was conducted on three proteins in vitro respectively (A: CaM, B: AdK, C: MBP). The total number and the inter-domain cross-linked pairs were indicated with the Venn diagrams. The cross-linked pairs captured by BS(PEG)₂ and BS³ were indicated, respectively. The structures of these proteins in the apo state are shown in the right panel, with different colors indicating the different structural domains and the linker between the structural domains. The inter-domain cross-linked sites are indicated by spheres, and the dotted lines between the spheres indicate the cross-links formed between them.