Predicted to enable cytochrome-b5 reductase activity, acting on NAD(P)H and nucleotide binding activity. Predicted to contribute to nitrite reductase (NO-forming) activity. Predicted to be involved in nitric oxide biosynthetic process. Predicted to act upstream of or within cholesterol biosynthetic process. Located in mitochondrial inner membrane. Is expressed in several structures, including alimentary system; brain; cardiovascular system; genitourinary system; and hemolymphoid system gland. Human ortholog(s) of this gene implicated in breast cancer and methemoglobinemia. Orthologous to human CYB5R3 (cytochrome b5 reductase 3). [provided by Alliance of Genome Resources, Apr 2022]