The function of ABCB8 (ATP binding cassette subfamily B member 8, ENSG00000197150) is as follows. ATP-binding subunit of the mitochondrial ATP-gated potassium channel (mitoK(ATP)) (PubMed:31435016). Together with pore-forming subunit CCDC51/MITOK of the mitoK(ATP) channel, mediates ATP-dependent potassium currents across the mitochondrial inner membrane (PubMed:31435016). An increase in ATP intracellular levels closes the channel, inhibiting K(+) transport, whereas a decrease in ATP levels enhances K(+) uptake in the mitochondrial matrix (PubMed:31435016). Plays a role in mitochondrial iron transport (PubMed:30623799). 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). {ECO:0000250|UniProtKB:Q9CXJ4, ECO:0000269|PubMed:30623799, ECO:0000269|PubMed:31435016}.