The transport of heme across membranes is critical for iron absorption, the formation of hemoglobin and other hemoproteins, and iron recycling in macrophages. However, the identity of heme transport proteins has been elusive. In this issue of the JCI, Chiabrando et al. reveal that an isoform of the feline leukemia virus subgroup C receptor (FLVCR1) exports heme from the mitochondria and is critical for erythroid differentiation.
Mark D. Fleming, Iqbal Hamza
Two isoforms of FLVCR1 may regulate heme levels.
FLVCRa isoform had previously been postulated to transport cytosolic heme across the plasma membrane. Chiabrando et al. now show that a mitochondrial isoform, FLVCR1b, transports heme from the mitochondria into the cytosol and thus is critical for the synthesis of hemoglobin and differentiation of erythroid cells.