Essential for sustained cell growth, maintenance of chromosomal stability, and ATR-dependent checkpoint activation upon DNA damage (PubMed:10208430, PubMed:11418864, PubMed:11687627, PubMed:11799063, PubMed:12672690, PubMed:14624239, PubMed:15235112). Has a weak ATPase activity required for binding to chromatin (PubMed:10208430, PubMed:11418864, PubMed:11687627, PubMed:11799063, PubMed:12672690, PubMed:14624239, PubMed:15235112). Participates in the recruitment of the 9-1-1 (RAD1-RAD9-HUS1) complex and RHNO1 onto chromatin, and in CHEK1 activation (PubMed:21659603). Involved in homologous recombination by mediating recruitment of the MRN complex to DNA damage sites (PubMed:24534091). May also serve as a sensor of DNA replication progression (PubMed:12578958, PubMed:14500819, PubMed:15538388). {ECO:0000269|PubMed:10208430, ECO:0000269|PubMed:11418864, ECO:0000269|PubMed:11687627, ECO:0000269|PubMed:11799063, ECO:0000269|PubMed:12578958, ECO:0000269|PubMed:12672690, ECO:0000269|PubMed:14500819, ECO:0000269|PubMed:14624239, ECO:0000269|PubMed:15235112, ECO:0000269|PubMed:15538388, ECO:0000269|PubMed:21659603, ECO:0000269|PubMed:24534091}. This is the function of RAD17 (RAD17 checkpoint clamp loader component, ENSG00000152942).