Packaging of telomere ends

Stable Identifier
Reaction [binding]
Gallus gallus
extended & processed duplex telomere end + shelterin -> shelterin:telomere with t-loop complex
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The fully replicated chromosome end associates with the shelterin protein complex and forms a structure in which the 3' G rich single strand overhang at the chromosome end loops around (t loop), invades the double stranded portion of the telomeric TTAGGG repeat tract displacing a strand and forming what is termed a D-loop (Griffith et al. 1999). This organization protects chromosome ends from degradation due to activation of DNA repair processes such as nonhomologous end joining (Nikitina and Woodcock 2004; Palm and de Lange 2008). Loops associated with TRF1 protein have been visualized in purified chicken telomeric chromatin (Nikitina and Woodcock 2004).

The human shelterin complex (Liu et al. 2004; Palm and de Lange 2008) contains six proteins, TRF1, TRF2, POT1, RAP1 (TERF2IP, TRF2IP), TPP1 (ACD), and TIN2 (TINF2). Chicken proteins homologous to the first four of these have been identified: TRF1 (Okamoto et al. 2008), TRF2 (Konrad et al. 1999), POT1 (Wei and Price 2004; Churikov et al. 2006), and TRF2IP (Tan et al. 2003). A possible chicken ortholog of TPP1 has been identified, but to date no chicken counterpart of human TIN2 has been found.

Literature References
PubMed ID Title Journal Year
18680434 How shelterin protects mammalian telomeres

de Lange, T, Palm, W

Annu Rev Genet 2008
18587156 Distinct roles of TRF1 in the regulation of telomere structure and lengthening

Okamoto, K, Shinkai, Y, Tachibana, M, Iwano, T

J Biol Chem 2008
14659874 The telomeric protein Rap1 is conserved in vertebrates and is expressed from a bidirectional promoter positioned between the Rap1 and KARS genes

Wei, C, Price, CM, Tan, M

Gene 2003
15249582 Closed chromatin loops at the ends of chromosomes

Nikitina, T, Woodcock, CL

J Cell Biol 2004
10571037 Cloning and characterisation of the chicken gene encoding the telomeric protein TRF2

Easty, DJ, Farr, CJ, Konrad, JP, Mills, W

Gene 1999
14966288 Cell cycle localization, dimerization, and binding domain architecture of the telomere protein cPot1

Wei, C, Price, CM

Mol Cell Biol 2004
16943437 Vertebrate POT1 restricts G-overhang length and prevents activation of a telomeric DNA damage checkpoint but is dispensable for overhang protection

Churikov, D, Wei, C, Price, CM

Mol Cell Biol 2006
15383534 Telosome, a mammalian telomere-associated complex formed by multiple telomeric proteins

O'Connor, MS, Songyang, Z, Qin, J, Liu, D

J Biol Chem 2004
10338214 Mammalian telomeres end in a large duplex loop

Moss, H, Bianchi, A, de Lange, T, Stansel, RM, Rosenfield, S, Comeau, L, Griffith, JD

Cell 1999
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