Enables glutathione-disulfide reductase (NADPH) activity. Predicted to be involved in several processes, including cell redox homeostasis; cellular response to oxidative stress; and glutathione metabolic process. Located in external side of plasma membrane. Is expressed in brain ventricular layer; gut; lung; metanephros; and retina. Human ortholog(s) of this gene implicated in cataract and macular degeneration. Orthologous to human GSR (glutathione-disulfide reductase). [provided by Alliance of Genome Resources, Apr 2022]