The Fanconi anemia ID complex consists of two subunits, Fanconi anemia I and Fanconi anemia D2 (FANCI-FANCD2) and plays a central role in the repair of DNA interstrand cross-links (ICLs). The complex is activated via DNA damage-induced phosphorylation by ATR (ataxia telangiectasia and Rad3-related) and monoubiquitination by the FA core complex ubiquitin ligase, and it binds to DNA at the ICL site, recognizing branched DNA structures. Defects in the complex cause Fanconi anemia, a cancer predisposition syndrome. The phosphorylation of FANCI may function as a molecular switch to turn on the FA pathway.
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