BLM

ATP-dependent DNA helicase that unwinds double-stranded (ds)DNA in a 3'-5' direction. Participates in DNA replication and repair. Involved in 5'-end resection of DNA during double-strand break (DSB) repair: unwinds DNA and recruits DNA2 which mediates the cleavage of 5'-ssDNA. Stimulates DNA 4-way junction branch migration and DNA Holliday junction dissolution. Binds single-stranded DNA (ssDNA), forked duplex DNA and Holliday junction DNA. Unwinds G-quadruplex DNA; unwinding occurs in the 3'-5' direction and requires a 3' single-stranded end of at least 7 nucleotides. Helicase activity is higher on G-quadruplex substrates than on duplex DNA substrates. Telomeres, immunoglobulin heavy chain switch regions and rDNA are notably G-rich; formation of G-quadruplex DNA would block DNA replication and transcription. Negatively regulates sister chromatid exchange (SCE). Recruited by the KHDC3L-OOEP scaffold to DNA replication forks where it is retained by TRIM25 ubiquitination, it thereby promotes the restart of stalled replication forks (By similarity)..

Function from UniProtKB (P54132), read 2026-09-23. CC BY 4.0.