Figure 1.

Schematic telomere structure and essential components. Human telomeric repeated DNA is protected by the shelterin complex, which consists of the protein components TRF1, TRF2, RAP1, TIN2, TPP1, and POT1. The ends of telomeres are bonded with telomerase, which is comprised of the catalytic subunit of TERT and the telomerase RNA component of TERC, and this exerts its effects by adding telomeric sequences to the telomeric ends. The telomerase also has other accessory components, including dyskerin, NHP2, NOP10, and GAR1. The function of these accessory components is to stabilize the TERC.