Recent studies have resulted in deeper understanding of a variety of telomere maintenance mechanisms as well as plausible models of telomere evolution. Often overlooked in the discussion of telomere regulation and evolution is the synthesis of the DNA strand that bears the 5′-end (i.e., the C-strand). Herein, I describe a scenario for telomere evolution that more explicitly accounts for the evolution of the C-strand synthesis machinery. In this model, CTC1-STN1-TEN1 (CST), the G-strand-binding complex that regulates primase-Pol α-mediated C-strand synthesis, emerges as a pivotal player and evolutionary link. Itself arising from RPA, CST not only coordinates telomere synthesis, but also gives rise to the POT1-TPP1 complex, which became part of shelterin and regulates telomerase in G-strand elongation.

最近的研究使人们对各种端粒维持机制以及端粒进化的合理模型有了更深入的了解。在端粒调控和进化的讨论中经常被忽视的是带有 5' 端的 DNA 链（即 C 链）的合成。在这里，我描述了端粒进化的一个场景，它更明确地解释了 C 链合成机制的进化。在该模型中，CTC1-STN1-TEN1 (CST) 是调节 primase-Pol α 介导的 C 链合成的 G 链结合复合物，成为关键参与者和进化环节。CST 本身由 RPA 产生，不仅协调端粒合成，而且产生 POT1-TPP1 复合物，它成为庇护素的一部分并在 G 链延伸中调节端粒酶。