Binds preferentially and cooperatively to pyrimidine rich single-stranded DNA (ss-DNA) ( ). In vitro, required to maintain the copy number of mitochondrial DNA (mtDNA) and plays a crucial role during mtDNA replication by stimulating the activity of the replisome components POLG and TWNK at the replication fork (  ). Promotes the activity of the gamma complex polymerase POLG, largely by organizing the template DNA and eliminating secondary structures to favor ss-DNA conformations that facilitate POLG activity ( ). In addition it is able to promote the 5'-3' unwinding activity of the mtDNA helicase TWNK . May also function in mtDNA repair .
Subcellular locations: Mitochondrion, Mitochondrion matrix, Mitochondrion nucleoid
Expressed in retinal ganglion cells, photoreceptors, pigmented epithelium and fibroblasts (at protein level).