Mitochondrial helicase involved in mtDNA replication and repair (   , ). Might have a role in mtDNA repair . Has DNA strand separation activity needed to form a processive replication fork for leading strand synthesis which is catalyzed by the formation of a replisome complex with POLG and mtSDB (  , ). Preferentially unwinds DNA substrates with pre-existing 5'-and 3'- single-stranded tails but is also active on a 5'- flap substrate (  , ). Can dissociate the invading strand of immobile or mobile D-loop DNA structures irrespective of the single strand polarity of the third strand . In addition to its DNA strand separation activity, also has DNA strand annealing, DNA strand-exchange and DNA branch migration activities ( ).
Lack DNA unwinding and ATP hydrolysis activities . Does not bind single-stranded or double-stranded DNA .
Subcellular locations: Mitochondrion matrix, Mitochondrion nucleoid, Mitochondrion inner membrane
Colocalizes with mtDNA in mitochondrial nucleoids, a nucleoproteins complex consisting of a number of copies of proteins associated with mtDNA, probably involved in mtDNA maintenance and expression . Associates with phospholipid membranes via electrostatic binding (By similarity). Preferentially associates with membranes enriched with cardiolipin, a lipid abundant in the mitochondrial inner membrane . ATPase and helicase activity is enhanced by binding to lipid membranes .
High relative levels in skeletal muscle, testis and pancreas. Lower levels of expression in the heart, brain, placenta, lung, liver, kidney, spleen, thymus, prostate, ovary, small intestine, colon and leukocytes. Expression is coregulated with MRPL43.