Which component of the DNA damage response (DDR) is associated with single-strand DNA breaks?
Different lesions within DNA damage response activate distinct kinase cascades tailored to repair requirements. Single-strand breaks, gaps, and regions of single-stranded DNA generated when replication forks stall at UV photoproducts or chemical adducts expose stretches of RPA-coated ssDNA that recruit ATR-ATRIP complex and auxiliary proteins TopBP1 and ETAA1. ATR, ataxia telangiectasia and Rad3-related kinase, then phosphorylates CHK1 at serine 317 and 345, leading to degradation of Cdc25A and inhibition of CDK2 to slow S-phase progression and allow repair via homologous recombination or tran
Ref: Cimprich & Cortez, Nature Rev Mol Cell Biol 2008, ATR: Essential Regulator of Genome Integrity; Zou & Elledge, Science 2003, ATR Activation.
