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. Author manuscript; available in PMC: 2013 Jun 23.
Published in final edited form as: Exp Dermatol. 2011 Mar 3;20(4):297–302. doi: 10.1111/j.1600-0625.2010.01242.x

Figure 1.

Figure 1

Telomere Structure. Human telomeres are regions of DNA that cap the ends of chromosomes and consist of 8–15 kb of repeats of the hexamer TTAGGG that terminates in a 3′ G-rich overhang. The DNA of telomeres is found complexed with a large number of proteins, including the six that comprise the shelterin complex: telomeric-repeat binding factor 1 (TRF1), TRF2, RAP1, TIN2, TPP1 and POT1. These proteins help create a protective structure at chromosome ends, known as the telomeric loop (or t loop). The single-stranded G-rich overhang invades the double-stranded helix of the telomere, protecting the single-stranded DNA (now in the displacement, or D loop) from detection by DNA damage machinery. See text for references.