Enables protein homodimerization activity and thioredoxin-disulfide reductase (NADPH) activity. Involved in cell redox homeostasis. Located in mitochondrion. Is expressed in adult brain; adult brain cell body rind; adult head; adult heart; and organism. Human ortholog(s) of this gene implicated in familial glucocorticoid deficiency. Orthologous to human TXNRD2 (thioredoxin reductase 2).