A “cap” protects the telomere at the end of a chromosome. The 3′ overhang is “hidden” when it displaces a DNA strand in a region where the telomeric repeats are double stranded. The proteins TRF1 and TRF2 bind to the telomeric repeats, and other proteins, including WRN, bind to TRF1 and TRF2, thus forming the protective telomeric cap.