ATP-binding subunit of the mitochondrial potassium channel located in the mitochondrial inner membrane (By similarity). Together with CCDC51/MITOK, forms a protein complex localized in the mitochondria that mediates ATP-dependent potassium currents across the inner membrane (that is, mitoK(ATP) channel) (By similarity). Plays a role in mitochondrial iron transport (PubMed:22375032). Required for maintenance of normal cardiac function, possibly by influencing mitochondrial iron export and regulating the maturation of cytosolic iron sulfur cluster-containing enzymes (PubMed:22375032). Channel activity inhibited by ATP via ABCB8/MITOSUR subunit. The mitochondrial potassium channel (mitoK(ATP)) is composed of 4 subunits of CCDC51/MITOK and 4 subunits of ABCB8/MITOSUR (By similarity). Interacts with PAAT (By similarity). Interacts with NRP1; NRP1 regulates ABCB8/MITOSUR protein levels in mitochondria (By similarity). Conditional knockout in heart results in a severe cardiomyopathy and mitochondrial iron accumulation. Belongs to the ABC transporter superfamily. ABCB family. Multidrug resistance exporter (TC 3.A.1.201) subfamily.