Replication termination factor which is a component of the elongating replisome (Probable). Required for ATR pathway signaling upon DNA damage and has a positive activity during DNA replication. Might function to facilitate fork pausing at replication fork barriers like the rDNA. May be globally required to stimulate ATR signaling after the fork stalls or encounters a lesion (Probable). Interacts with nascent DNA (PubMed:29290612).