Fig. 2. Structure of the telomere.

A Replication of telomeres which shorten at each cell division and terminates with a 3-ssDNA-end G-rich overhang extremity. B Telomeres, located at the chromosome termini, are capped by the shelterin complex comprising six proteins. TRF1 and TRF2, which form homodimers, interact with the telomeric dsDNA form whereas POT1 is associated with telomeric ssDNA at the 3′ overhang. TIN2 acts as a bridge between these two homodimers. The telomere likely exists in a dynamic equilibrium as a linear structure with a free 3′ overhang (to the top) and the T-loop structure (below).