(A) SOS1 missense mutations are positioned below the cartoon of the SOS1 protein with its functional domains indicated above. Abbreviations: DH, Dbl homology domain; PH, plekstrin homology domain; Rem, RAS exchanger motif; PxxP, proline-rich region. (B) Location of the mutated residues on the three-dimensional structure of SOS1. The functional domains are color coded as follows: Histone folds, cyan; DH, magenta; PH, orange; Rem, green; Cdc25, yellow. Residues affected by mutations are indicated with their lateral chains (histone folds, violet; DH, blue; PH, green; helical linker, red; Rem, orange; Cdc25, cyan). Based on Sondermann et al.121, which utilized structural data and computational modeling.