Fig. 1.

Mechanism of ATR activation in response to DNA Lesions. ATR activation at DNA damage sites mainly comprises two steps; [I] recognition and recruitment of ATR at DNA lesions; followed by [II] localized activation of ATR and subsequent initiation of DNA damage response pathway. ssDNA-RPA complex assist efficient recruitment of ATR-ATRIP and 9-1-1 complex on DNA damaged regions. Finally, TopBP1 and other proteins recruited to the sites and potentiate ATR activation. PTMs on RPA, ATRIP and ATR (depicted) also play a crucial role (feed back loop) in achieving complete ATR activation.