Enables transferrin receptor binding activity. Involved in positive regulation of gene expression. Acts upstream of or within hormone biosynthetic process and multicellular organismal iron ion homeostasis. Part of HFE-transferrin receptor complex. Is expressed in brain; choroid invagination; diencephalon roof plate; medulla oblongata part of 4th ventricle choroid plexus; and metencephalon part of 4th ventricle choroid plexus. Used to study hemochromatosis type 1. Human ortholog(s) of this gene implicated in several diseases, including acute porphyria (multiple); arthritis (multiple); bone marrow cancer (multiple); hemochromatosis (multiple); and liver disease (multiple). Orthologous to human HFE (homeostatic iron regulator). [provided by Alliance of Genome Resources, Apr 2022]