Polypeptide components of telomere nucleoprotein complex.

Chromosome telomeres of humans and many model organisms contain a structure called a t-loop, which is maintained by TERF, TINF2, Pot1, and other proteins. Increase in TERF1 concentration prevents telomere elongation by telomerase. Decrease in TERF2 concentration (preventing t-loop formation) is accompanied by blockade of proliferation and appearance of other signs of cellular senescence in experiments. Natural regulation of TERF1 involves tankyrase, ATM protein kinase, and fluctuations of the protein level across a cell cycle. The telomere nucleoprotein complex also interacts with various polypeptide macromolecules (e.g., Sir2, PinX1, Rap1, Ku, Rad50/Mre11/Nbs1) responsible for heterochromatin formation, modulation of telomerase activity, DNA repair, and signaling to other cell compartments about telomere state. Study of structure and functioning of telomere nucleoprotein complex may contribute to elucidation of poorly understood mechanisms of aging and processes of tumor transformation of cells.