Ferric-chelate reductases reduce Fe(3+) to Fe(2+) before its transport from the endosome to the cytoplasm. Binds 2 heme b groups non-covalently. Expressed in spleen, liver and kidney with low expression in brain. Localizes in adult brain to the choroid plexus of the fourth, third, and lateral ventricles and to ependymal cells that line the ventricles. Down-regulated in kidney and liver of mice lacking hypotransferrinemic (hpx), which have iron overload of the liver and pancreas. Belongs to the FRRS1 family.