Anti-DNA helicase B (HELB) from rabbit

DNA helicase B (UniProt: Q8NG08; also known as EC: 3.6.4.12, hDHB) is encoded by the HELB gene (Gene ID: 92797) in human. DNA helicase B is highly expressed in testis and thymus and weaker expression is observed in liver, spleen, kidney, and brain. It is predominantly nuclear, however, following phosphorylation at serine 967 by CDK2 during the G1/S transition it is exported into the cytoplasm. Following DNA damage, it is recruited to sites of double-strand breaks by the RPA complex. Its recruitment to single-stranded DNA following DNA damage leads to inhibition of 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 its phosphorylation. Its nuclear export signal is localized to amino acids 1055-1078. It uses either magnesium or manganese ions to support its helicase activity and the DNA helicase B activity is inhibited by salt concentrations higher than 100 mM. It binds strongly to single-stranded DNA in the absence of ATP, but dissociates readily in the presence of 1 mM ATP. Two isoforms of DNA helicase B have been reported that are produced by alternative splicing.