Thiol-disulfide oxidoreductase that may participate in various redox reactions. May activate NADP-malate dehydrogenase. Interacts with G6PD1 and G6PD4 (PubMed:21309870). Interacts with PGL3 (PubMed:24008768). A number of isoforms are produced. According to EST sequences. Belongs to the thioredoxin family. Plant M-type subfamily.