Telomere-binding protein that acts as a regulator of telomere length (PubMed:28082411, PubMed:28500257). Directly binds the telomeric double-stranded 5′-TTAGGG-3′ repeat (PubMed:28082411, PubMed:28500257). Preferentially binds to telomeres that have a low concentration of shelterin complex and acts as a regulator of telomere length by initiating telomere trimming, a process that prevents the accumulation of aberrantly long telomeres (PubMed:28082411). Also acts as a transcription regulator that binds to promoter regions (PubMed:24382891, PubMed:28500257, PubMed:7969177). Regulates expression of a small subset of genes, including MTFP1 (PubMed:28500257). Regulates expression the J and/or S elements in MHC II promoter (PubMed:7969177). Acts as a negative regulator of cell proliferation by specifically activating expression of ARF, a tumor suppressor isoform of CDKN2A (PubMed:24382891).
