Putative heme b importer/sensor involved in heme homeostasis in response to the metabolic state of the cell and to diet. May act as a sensor of cytosolic and/or mitochondrial heme levels to regulate mitochondrial respiration processes, ATP synthesis and thermogenesis. At low heme levels, interacts with components of electron transfer chain (ETC) complexes and ATP2A2, leading to ubiquitin-mediated degradation of ATP2A2 and inhibition of thermogenesis. Upon heme binding, dissociates from ETC complexes to allow switching from mitochondrial ATP synthesis to thermogenesis. Alternatively, in coordination with ATP2A2 may mediate calcium transport and signaling in response to heme.
