Telomeres are specialized structures, found at the ends of linear chromosomes in eukaryotic cells, that play a crucial role in maintaining the stability and integrity of genomes. They are composed of repetitive DNA sequences, ssDNA overhangs, and several associated proteins. The length of telomeres is linked to cellular aging in humans, and deficiencies in their maintenance are associated with various diseases. Key structural motifs at the telomeres serve to protect vulnerable chromosomal ends. Telomeric DNA also has the ability to form diverse complex DNA higher-order structures, including T-loops, D-loops, R-loops, G-loops, G-quadruplexes, and i-motifs, in the complementary C-rich strand. While many essential proteins at telomeres have been identified, the intricacies of their interactions and structural details are still not fully understood. This Perspective highlights recent advancements in comprehending the structures associated with human telomeres. It emphasizes the significance of telomeres, explores various telomeric structural motifs, and delves into the structural biology surrounding telomeres and telomerase. Furthermore, telomeric loops, their topologies, and the associated proteins that contribute to the safeguarding of telomeres are discussed.

中文翻译：

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端粒的结构基序及其在调控途径中的作用

端粒是在真核细胞线性染色体末端发现的特殊结构，在维持基因组的稳定性和完整性方面发挥着至关重要的作用。它们由重复的 DNA 序列、ssDNA 突出端和一些相关蛋白组成。端粒的长度与人类细胞的衰老有关，端粒维持的缺陷与多种疾病有关。端粒的关键结构基序用于保护脆弱的染色体末端。端粒 DNA 还能够在互补的富含 C 链中形成多种复杂的 DNA 高阶结构，包括 T 环、D 环、R 环、G 环、G 四链体和 i 基序。虽然端粒上的许多必需蛋白质已被鉴定，但它们的相互作用和结构细节的复杂性仍不完全清楚。本观点强调了理解人类端粒相关结构的最新进展。它强调端粒的重要性，探索各种端粒结构基序，并深入研究端粒和端粒酶周围的结构生物学。此外，还讨论了端粒环、它们的拓扑结构以及有助于保护端粒的相关蛋白质。