TRF-2: Proteins and Enzymes

RF2 (telomeric repeat-binding factor 2; also telomeric DNA-binding protein) is a 55-60 kDa, ubiquitously expressed nuclear protein that participates in telomere homeostasis. TRF2 binds as a dimer to TTAGGG repeats at ends of chromosomes (telomeres), where it blocks inappropriate activation of the ATM/p53 pathway. It also collaborates with TRF1 to promote normal telomere length. TRF2 has been found up regulated in several human cancers. Human TRF2 is 500 amino acids (aa) in length. It contains an N-terminal Arg-rich region (aa 13-30), a dimerization domain (aa 46-112), an NLS (aa 329-333), and a DNA binding HTH myb-type domain (aa 442-499). There is one potential alternate start site 42 aa upstream of the standard start site, and one splice form that shows a 13 aa substitution for aa 239-500. Over aa 78-238, human TRF2 shares 96% aa identity with mouse TRF2.