Enables heme binding activity and transmembrane ascorbate ferrireductase activity. Predicted to be involved in ascorbate homeostasis. Located in endoplasmic reticulum and vesicle. Is expressed in Meckel's cartilage; genitourinary system; lower leg mesenchyme; skeleton; and thymus. Orthologous to human CYB561D2 (cytochrome b561 family member D2). [provided by Alliance of Genome Resources, Apr 2022]