TERF2 Protein, Human (His, Strep)

TERF2 is a protein that binds the telomeric double-stranded 5'-TTAGGG-3' repeat and plays a central role in telomere maintenance and protection against end-to-end fusion of chromosomes. Beyond its telomeric DNA-binding function, it recruits multiple factors and enzymes essential for telomere protection, including the shelterin complex, TERF2IP/RAP1, and DCLRE1B/Apollo. As a component of the shelterin complex (telosome), TERF2 regulates telomere length and shields chromosome ends from DNA damage surveillance and inappropriate processing by DNA repair pathways. Collaborating with DCLRE1B/Apollo, TERF2 is crucial for telomeric loop (T loop) formation by generating 3' single-stranded overhangs at leading-end telomeres, protecting them from degradation and repair. It also recruits and activates the exonuclease activity of DCLRE1B/Apollo, preferentially binds positive supercoiled DNA, and, together with DCLRE1B/Apollo, controls DNA topoisomerase (TOP1, TOP2A, and TOP2B) levels during telomere replication to prevent aberrant topology. By similarity, TERF2 recruits TERF2IP/RAP1 to telomeres, contributing to the repression of homology-directed repair (HDR), which may influence telomere length.