ATP-binding subunit of the mitochondrial potassium channel located in the mitochondrial inner membrane. 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. Required for maintenance of normal cardiac function, possibly by influencing mitochondrial iron export and regulating the maturation of cytosolic iron sulfur cluster-containing enzymes (By similarity). 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. Physically interacts with PAAT. Interacts with Neuropilin-1 (NRP1) in mitochondria. Strong expression is found in the heart, brain and testis (PubMed:16390497). In the testis, expressed both in the somatic Sertoli cells and peritubular cells and in the germline (spermatogonia and pachytene spermatocytes) (PubMed:16390497). Also expressed in the lung, liver, intestine and kidney (PubMed:16390497). Belongs to the ABC transporter superfamily. ABCB family. Multidrug resistance exporter (TC 3.A.1.201) subfamily.