Telomeres: Protection and Maintenance


Eukaryotic chromosomes terminate in telomeres, nucleoprotein complexes thought to mask chromosome ends from the machinery that detects and repairs damaged deoxyribonucleic acid (DNA). The maintenance of this protective telomeric cap requires a specialized mode of DNA synthesis, because chromosome duplication results in incomplete replication of DNA ends. Proteins associated with the telomeric DNA sequence at chromosome ends execute and regulate the maintenance and protection functions of telomeres.

Keywords: telomere; telomerase; cancer; chromosome; genome instability

Figure 1.

Proteins associated with human telomeres. Additional components (not shown) are Ku, DNA‐PKcs and the RECQ helicases BLM and WRN (see text for details).

Figure 2.

Dynamics of human telomeres.

Figure 3.

Model of telomere length regulation by TRF1.

Figure 4.

T‐loop model of telomere protection and length regulation.



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Further Reading

Blackburn EH and Greider CW (eds.) (1995) Telomeres Cold Spring Harbor, NY: Cold Spring Harbor Press.

Collins K (2000) Mammalian telomeres and telomerase. Current Opinion in Cell Biology 12(3): 378–383.

de Lange T (2001) Telomere capping – one strand fits all. Science 292: 1075–1076.

de Lange T and Jacks T (1999) For better or worse? Telomerase inhibition and cancer. Cell 98: 273–275.

McEachern MJ, Krauskopf A and Blackburn EH (2000) Telomeres and their control. Annual Review of Genetics 34: 331–358.

Nugent CI and Lundblad V (1998) The telomerase reverse transcriptase: components and regulation. Genes and Development 12: 1073–1085.

Oulton R and Harrington L (2000) Telomeres, telomerase, and cancer: life on the edge of genomic stability. Current Opinion in Oncology 12: 74–81.

Sherr CJ and DePinho RA (2000) Cellular senescence: mitotic clock or culture shock? Cell 102: 407–410.

Web Links

TERF2(telomeric repeat binding factor 2); LocusID: 7014. LocusLink:

TERT(telomerase reverse transcriptase); LocusID: 7015. LocusLink:

TERF2(telomeric repeat binding factor 2); MIM number: 602027. OMIM:‐post/Omim/dispmim?602027

TERT(telomerase reverse transcriptase); MIM number: 187270. OMIM:‐post/Omim/dispmim?187270

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How to Cite close
de Lange, Titia(Sep 2005) Telomeres: Protection and Maintenance. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0005281]