Extended Data Fig. 6: Cross-linking mass spectrometry of NF1.
a. Cross-linking mass spectrometry identified a total of 174 BS2G cross-links and 72 BS3 cross-links within the NF1 dimer. b. Mapping of the BS2G cross-links onto the NF1 structure revealed that the cross-links mapped to allowable regions of the NF1 model. Cα carbons of cross-linked residues are shown as spheres and lines indicate cross-linked residues. Cross-links are shown for a single chain only for clarity. c. Circos plot highlighting all BS3 and BS2G cross-links observed between the GRD domain and the rest of the NF1 molecule. GRD cross-linked regions map remarkably well to the two known NF1 phosphor-regulatory regions58. Known NF1 phosphorylation sites58 are indicated as dashed red lines on the inside of the Circos plot. d. Although these phosphor-regulatory regions are too flexible to appear in the cryo-EM maps, they are each situated adjacent to the GRDs and appear poised to further regulate either the conformation of the GRD or membrane binding capacity. Structural representation of the NF1 surface with the GRD and SEC-PH domains in cartoon format. The Cα carbon of the exit (C2432) and entry (P2596) residue of the main phosphor-regulatory loop are indicated as yellow spheres. The Cα carbon of the final resolved residue of the C-terminus (L2726) is also indicated as a yellow sphere. Cα carbons on the GRD that cross-link to the phosphor-regulatory loops are indicated as pink spheres.
