Purification and determination of iron content in FANCJ-WT and FANCJ-A349P proteins. (A) Cartoon depicting FANCJ protein with the conserved helicase core domain and position of the conserved Fe-S domain. The conserved helicase motifs are indicated by yellow boxes, and the BRCA1 binding domain is indicated by green. The Fe-S domain is expanded, and the 4 conserved cysteines are indicated with blue, with the A349P missense mutation of a FANCJ patient marked. (B) The purity of the FANCJ-WT and FANCJ-A349P proteins was evaluated by their detected migration after sulfate polyacrylamide gel electrophoresis (SDS-PAGE) on Coomassie-stained gels according to their predicted sizes. For each protein, 2 μg was loaded. (C) Stoichiometry of iron atoms per purified recombinant FANCJ-WT or FANCJ-A349P. The determination of iron content is described in supplemental Methods. Data represent the mean of at least 3 independent experiments, with SD indicated by error bars.