Figure 1. Human telomere components and structure.

Figure 1

Human telomere components and structure. A) Graphic representation of the telomeric DNA in human cells, which is normally composed of 4-12 kb of G-rich repeats (TTAGGG in red, AATCCC in blue), culminating in a 100-200 nt 3' overhang. Open and t-loop configurations are shown. B) Graphic representation of telomeric DNA with associated proteins. The six subunit “shelterin” or “telosome” complex coats the length of the duplex telomeric DNA via the direct interaction of TRF1 and TRF2 with telomeric DNA. TIN2 interacts with both TRF1 and TRF2 but not with telomeric DNA. TPP1 (formerly PTOP, PIP1 or TINT1) bridges TIN2 with POT1. POT1 interacts specifically with single-stranded G-rich telomeric DNA, presumably at the chromosome end when the telomere is in open configuration, or at the single-stranded region within the t-loop junction. Telomeres are also assembled into chromatin.

From: Alternative Lengthening of Telomeres in Mammalian Cells

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