5'-3' DNA helicase involved in DNA damage response by acting as an inhibitor of DNA end resection (, ). Recruitment to single-stranded DNA (ssDNA) following DNA damage leads to inhibit the nucleases catalyzing resection, such as EXO1, BLM and DNA2, possibly via the 5'-3' ssDNA translocase activity of HELB . As cells approach S phase, DNA end resection is promoted by the nuclear export of HELB following phosphorylation . Acts independently of TP53BP1 . Unwinds duplex DNA with 5'-3' polarity. Has single-strand DNA-dependent ATPase and DNA helicase activities. Prefers ATP and dATP as substrates . During S phase, may facilitate cellular recovery from replication stress .
Subcellular locations: Nucleus, Cytoplasm, Chromosome
Predominantly nuclear . Phosphorylation at Ser-967 by CDK2 during the G1/S transition results in its nuclear export into the cytoplasm as cells approach and progress through S phase . Following DNA damage, recruited to sites of double-strand breaks by the RPA complex . Recruited to chromatin following DNA damage induced by UV irradiation, or camptothecin or hydroxyurea treatment .
Highly expressed in testis and thymus and weakly in liver, spleen, kidney and brain.