Has a glutathione-disulfide oxidoreductase activity in the presence of NADPH and glutathione reductase. Reduces low molecular weight disulfides and proteins. Can assemble a [2Fe-2S] cluster, but cannot transfer it to an apoferredoxin. kcat is 1.21 sec(-1) with glutathionylated beta-mercaptoethanol as substrate. kcat is 0.23 sec(-1) with dehydroascorbate as substrate. kcat is 0.69 sec(-1) with reduced glutathione as substrate. Monomeric apoprotein and homodimeric holoprotein containing a [2Fe-2S] cluster (PubMed:21632542). No in vitro interactions with SUFE1, BOLA1, BOLA2 or BOLA4 (PubMed:24203231). Up-regulated by cold treatment. Glutathionylated. Belongs to the glutaredoxin family. CPYC subfamily.