端粒酶介导的端粒延伸
中文名称
通路描述
人类像大多数真核生物一样，使用一种特殊的 DNA 聚合酶端粒酶在端粒处添加直接重复序列。端粒酶是一种核糖核蛋白复合物（RNP），其最小组成包括一个保守的蛋白亚基，该亚基包含逆转录酶结构域（人类端粒酶逆转录酶，hTERT）和一个模板含 RNA（人类端粒酶 RNA 组分，hTERC，或 hTR, hTER）。端粒酶的引物是染色体末端处的 G 富集单链悬突。端粒酶可以进行多次重复合成。反应循环已从多种生物的端粒酶体外研究推断，可描述为包含四个事件：1）DNA 引物识别，2）RNA 模板对齐，3）延伸，4）转位。端粒 DNA 部分由 hTERT 中假定的“锚定位点”识别，该位点偏好结合 G 富集 DNA，这种相互作用可以影响延伸和转位步骤。这种相互作用发生在 RNA 模板与染色体末端核苷酸对齐的 5'侧。RNA 对齐将模板定位在染色体末端附近。在延伸过程中，模板指导核苷酸的顺序添加到端粒末端。重复合成完成后，端粒酶和引物的相对移动，称为转位，将端粒酶重新定位到新添加序列的末端，以允许再次启动重复添加。
英文描述
Telomere Extension By Telomerase Humans, like most eukaryotic organisms, add direct repeats to the telomere using a specialized DNA polymerase called telomerase. Telomerase is a ribonucleoprotein (RNP) complex minimally composed of a conserved protein subunit containing a reverse transcriptase domain (human telomerase reverse transcriptase, hTERT) and a template-containing RNA (human telomerase RNA component, hTERC, or hTR, hTER). The primer for telomerase is the G-rich single-strand overhang at the chromosome end.
Telomerase can perform multiple rounds of repeat synthesis. The reaction cycle has been inferred from in vitro studies of telomerase from multiple organisms and can be described as having four events: 1) DNA primer recognition, 2) RNA template alignment, 3) elongation, and 4) translocation. Telomeric DNA is recognized in part by a presumed "anchor site" in hTERT, which preferentially binds G-rich DNA, and this interaction can affect elongation and translocation steps. This interaction occurs 5' of the alignment of the RNA template with the end nucleotides of the chromosome. RNA alignment positions the template adjacent to the chromosome terminus. During elongation, the template directs sequential addition of nucleotides to the telomere end. After synthesis of a repeat is completed, relative movement of telomerase and the primer, termed translocation, repositions telomerase at the end of the newly added sequence to allow initiation of another round of repeat addition.
Telomerase can perform multiple rounds of repeat synthesis. The reaction cycle has been inferred from in vitro studies of telomerase from multiple organisms and can be described as having four events: 1) DNA primer recognition, 2) RNA template alignment, 3) elongation, and 4) translocation. Telomeric DNA is recognized in part by a presumed "anchor site" in hTERT, which preferentially binds G-rich DNA, and this interaction can affect elongation and translocation steps. This interaction occurs 5' of the alignment of the RNA template with the end nucleotides of the chromosome. RNA alignment positions the template adjacent to the chromosome terminus. During elongation, the template directs sequential addition of nucleotides to the telomere end. After synthesis of a repeat is completed, relative movement of telomerase and the primer, termed translocation, repositions telomerase at the end of the newly added sequence to allow initiation of another round of repeat addition.
所含基因
23 个基因