Essential for sustained cell growth, maintenance of chromosomal stability, and ATR-dependent checkpoint activation upon DNA damage (   ). Has a weak ATPase activity required for binding to chromatin (   ). Participates in the recruitment of the 9-1-1 (RAD1-RAD9-HUS1) complex and RHNO1 onto chromatin, and in CHEK1 activation . May also serve as a sensor of DNA replication progression, and may be involved in homologous recombination ( ).
Subcellular locations: Nucleus
Phosphorylated form redistributes to discrete nuclear foci upon DNA damage.
Overexpressed in various cancer cell lines and in colon carcinoma (at protein level). Isoform 2 and isoform 3 are the most abundant isoforms in non irradiated cells (at protein level). Ubiquitous at low levels. Highly expressed in testis, where it is expressed within the germinal epithelium of the seminiferous tubuli. Weakly expressed in seminomas (testicular tumors).