The genomes of prokaryotes and eukaryotic organelles are usually circular as are most plasmids and viral genomes. In contrast, the nuclear genomes of eukaryotes are organized on linear chromosomes, which require mechanisms to protect and replicate DNA ends. Eukaryotes navigate these problems with the advent of telomeres, protective nucleoprotein complexes at the ends of linear chromosomes, and telomerase, the enzyme that maintains the DNA in these structures. Mammalian telomeres contain a specific protein complex, shelterin, that functions to protect chromosome ends from all aspects of the DNA damage response and regulates telomere maintenance by telomerase. Recent experiments, discussed here, have revealed how shelterin represses the ATM and ATR kinase signaling pathways and hides chromosome ends from nonhomologous end joining and homology-directed repair.

中文翻译：

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庇护素如何保护哺乳动物的端粒。

如同大多数质粒和病毒基因组一样，原核生物和真核细胞器的基因组通常是环状的。相反，真核生物的核基因组组织在线性染色体上，这需要保护和复制DNA末端的机制。真核生物通过端粒，线性染色体末端的保护性核蛋白复合物以及端粒酶（将DNA保持在这些结构中的酶）的出现解决了这些问题。哺乳动物端粒包含一种特定的蛋白质复合物，避雷肽，其功能是保护染色体末端免受DNA损伤反应的各个方面的影响，并通过端粒酶调节端粒的维持。在这里讨论的最新实验，