Table 1.

The functions of the six protein subunits of the Shelterin complex. Adapted from Turner et al. [18], Shay et al. [37], and Bettin et al. [38]

Subunit	Interactions	Functions
TRF1	Binds to the double-stranded TTAGGG repeats; interacts with TIN2	Regulates telomere length
TRF2	Binds to the double-stranded TTAGGG repeats; interacts with RAP1	Regulates telomere length; stabilizes the T-loop
TIN2	Directly associated with TRF1, TRF2 & TPP1;indirectly associated with POT1	Regulates telomere length; secures TPP1 and POT1 to TRF1 and TRF2
POT1	Binds to single-stranded overhang; linked to TRF1 and TRF2 via TPP1	Regulates telomere length; prevents activation of DNA damage response
TPP1	Interacts with TIN2 and POT1	Regulates telomere length; strengthens the bond between POT1 and telomere
RAP1	Associated with TRF2	Regulates telomere length; increases affinity of TRF2 to the telomere