Single-stranded DNA-dependent ATP-dependent helicase. Involved in non-homologous end joining (NHEJ) DNA double strand break repair (By similarity). Sequence-specific DNA-binding protein that has a high affinity for a 31 bp sequence in the Yp1 gene. Site-specific DNA binding to 31 bp P element inverted repeats. ATP + H2O = ADP + H(+) + phosphate Heterodimer of a 70 kDa and a 80 kDa subunit. Expressed both maternally and zygotically, expression is at low levels in all stages of development. Belongs to the ku70 family.