PIF1 5"-To-3" DNA Helicase Homolog (PIF1)

PIF1 is a 5-prime-to-3-prime DNA helicase that negatively regulates telomerase, a reverse transcriptase that maintains telomere length.PIF1 reduced telomerase processivity and unwound telomeric DNA/telomerase RNA (TERC) duplexes in vitro, and it preferentially bound telomeric DNA in vitro and in vivo. PIF1 had a short half life, and its degradation was mediated by ubiquitination and proteasomal degradation. Abundance of PIF1 decreased following overexpression of an activator of the anaphase-promoting complex/cyclosome. PIF1 interacted with the catalytic telomerase subunit, TERT, and telomerase activity immunoprecipitated with PIF1 from human cell lines.