Cytochrome b(561), as found in vertebrates, which might act as a ferric-chelate reductase, catalyzing the reduction of Fe(3+) to Fe(2+), such as associated with the transport of iron from the endosome to the cytoplasm. It is assumed that this protein uses ascorbate as the electron donor. Belongs to the cytochrome b(561) family, which are secretory vesicle-specific electron transport proteins. Cytochromes b(561) are integral membrane proteins that bind two heme groups non-covalently, and may have six alpha-helical trans-membrane segments.
Jiyao W et al.(2023). "The conserved domain database in 2023.",