OSGEP and Galloway-Mowat syndrome: Based on the model of KEOPS–tRNA complex (Figure 3C) and loss-of-function mutations in HsOSGEP, we chose to characterize the functional sites of AtKAE1 (Figure 4B): (i) an extremely conserved H–H–D motif (H117 and D298) that coordinates the metal ion Fe2+ (32); (ii) I17, K202 and R284 that are equivalent to missense mutations (I14F, K198R, R280C) of HsOSGEP in GAMOS patients (16); (iii) non-conserved A231 and Y305 in the vicinity of the catalytic site of KAE1.