CIAO1 is essential component of the cytosolic iron-sulfur (Fe/S) protein assembly machinery. This protein is required for the maturation of extra mitochondrial Fe/S proteins and seems to specifically modulate the trans-activation activity of WT1. As part of the mitotic spindle-associated MMXD complex it may play a role in chromosome segregation. Recombinant human CIAO1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.