"5' to 3' DNA replicative helicase recruited to paused replisomes to promote fork progression throughout nonhistone protein-DNA complexes, naturally occurring impediments that are encountered in each S phase where replication forks pauses. Required for timely replication of the telomere and subtelomeric DNA and for wild-type levels of telomeric silencing. Involved in DNA repair during stalled replication fork, regulation of fragile sites expression and essential for genome stability. Plays also a role in mtDNA replication. Has G-quadruplex (G4) unwinding activity and can suppress G4-induced genome instability when PIF1 levels are low."xsd:string