Figure 7.

Models for [2Fe-2S]²⁺ Grx homodimers (left) and [2Fe-2S]²⁺ Grx-BolA heterocomplexes (right) characterized from E. coli, S. cerevisiae, and H. sapiens. In each case, Grx-BolA heterocomplexes can be formed by titration of Grx homodimers with the apo BolA-like protein. In all CGFS Grx homodimers, the active site cysteines in the Grx-like domains and 2 GSH molecules ligate the [2Fe-2S] clusters. For yeast and human Grx-BolA heterocomplexes, each [2Fe-2S] cluster is ligated by one Grx domain active site cysteine, one GSH, a histidine from the BolA-like protein and an unidentified 4^th ligand. For the E. coli [2Fe-2S]²⁺ Grx4-BolA heterodimer, the ligands provided by BolA have not been identified.