DCLRE1B: 5'-3' exonuclease that plays a central role in telomere maintenance and protection during S-phase. Participates in the protection of telomeres against non-homologous end-joining (NHEJ)- mediated repair, thereby ensuring that telomeres do not fuse. Plays a key role in telomeric loop (T loop) formation by being recruited by TERF2 at the leading end telomeres and by processing leading-end telomeres immediately after their replication via its exonuclease activity: generates 3' single-stranded overhang at the leading end telomeres avoiding blunt leading-end telomeres that are vulnerable to end-joining reactions and expose the telomere end in a manner that activates the DNA repair pathways. Together with TERF2, required to protect telomeres from replicative damage during replication by controlling the amount of DNA topoisomerase (TOP1, TOP2A and TOP2B) needed for telomere replication during fork passage and prevent aberrant telomere topology. Also involved in response to DNA damage: plays a role in response to DNA interstrand cross-links (ICLs) by facilitating double-strand break formation. In case of spindle stress, involved in prophase checkpoint. Defects in DCLRE1B may be a cause of Hoyeraal-Hreidarsson syndrome (HHS). HHS is a multisystem disorder affecting males and is characterized by aplastic anemia, immunodeficiency, microcephaly, cerebellar hypoplasia, and growth retardation. An aberrant splice variant designated Apollo- Delta has been found in a patient with Hoyeraal-Hreidarsson syndrome. Apollo-Delta hampers the proper replication of telomeres, leading to major telomeric dysfunction and cellular senescence, but maintains its DNA interstrand cross-link repair function in the whole genome. Belongs to the DNA repair metallo-beta-lactamase (DRMBL) family.
Protein type: DNA repair, damage; Hydrolase; EC 3.1.-.-
Chromosomal Location of Human Ortholog: 1p13.2
Cellular Component: centrosome; chromosome, telomeric region; cytoplasm; nucleus
Molecular Function: 5'-3' exonuclease activity; protein binding
Biological Process: telomeric loop formation; telomeric 3' overhang formation; DNA repair; telomere maintenance; cell cycle checkpoint; protection from non-homologous end joining at telomere
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