Acts as an importer of heme. Also acts as a transporter for a calcium-chelator complex, important for growth and calcium metabolism (By similarity). Found in the kidney and in cells implicated in rapid calcium exchange, namely the CNS, the eye, cardiomyocytes and placenta in late term. Found in fetal chondrocytes and osteoclasts. Belongs to the major facilitator superfamily. Feline leukemia virus subgroup C receptor (TC 2.A.1.28.1) family.