A HUMAN TELOMERIC PROTEIN

Telomeres are multifunctional elements that shield chromosome ends fro m degradation and end-to-end fusions, prevent activation of DNA damage checkpoints, and modulate the maintenance of telomeric DNA by telomer ase. A major protein component of human telomeres has been identified and cloned. This factor, TRF, contains one Myb-type DNA-binding repeat and an amino-terminal acidic domain. Immunofluorescent labeling shows that TRF specifically colocalizes with telomeric DNA in human interph ase cells and is located at chromosome ends during metaphase. The pres ence of TRF along the telomeric TTAGGG repeat army demonstrates that h uman telomeres form a specialized nucleoprotein complex.