May only reduce GSH-thiol disulfides, but not protein disulfides. Participates probably to the maturation of iron-sulfur proteins and to the regulation of the redox state of the BOLA proteins. [2Fe-2S]-bridged holo-homodimer (By similarity). Interacts in vitro with SUFE1, BOLA1, BOLA2 and BOLA4 (PubMed:24203231). Interacts in vivo only with BOLA4 (PubMed:24203231). Belongs to the glutaredoxin family. CGFS subfamily.