Baboo Sabyasachi, Cook Peter R
a Sir William Dunn School of Pathology; University of Oxford; Oxford, UK.
Nucleus. 2014 Jul-Aug;5(4):281-6. doi: 10.4161/nucl.29577.
Astrophysicists use the term "dark matter" to describe the majority of the matter and/or energy in the universe that is hidden from view, and biologists now apply it to the new families of RNA they are uncovering. We review evidence for an analogous hidden world containing peptides. The critical experiments involved pulse-labeling human cells with tagged amino acids for periods as short as five seconds. Results are extraordinary in two respects: both nucleus and cytoplasm become labeled, and most signals disappear with a half-life of less than one minute. Just as the synthesis of each mature mRNA is regulated by the abortive production of hundreds of shorter transcripts that are quickly degraded, it seems that the synthesis of each full-length protein in the stable proteome is regulated by an apparently wasteful production and degradation of shorter peptides. Some of the nuclear synthesis is probably a byproduct of nuclear ribosomes proofreading newly-made RNA for inappropriately-placed termination codons (a process that triggers "nonsense-mediated decay"). We speculate that some "dark-matter" peptides will play other important roles in the cell.
天体物理学家用“暗物质”一词来描述宇宙中大部分隐藏不见的物质和/或能量，而生物学家现在将其应用于他们正在发现的新的RNA家族。我们综述了关于存在类似隐藏肽类世界的证据。关键实验包括用标记氨基酸对人类细胞进行短至五秒的脉冲标记。结果在两个方面非同寻常：细胞核和细胞质都被标记，并且大多数信号的半衰期不到一分钟就消失了。正如每个成熟mRNA的合成受数百个迅速降解的较短转录本的流产性产生所调控一样，稳定蛋白质组中每个全长蛋白质的合成似乎也受较短肽段明显的浪费性产生和降解所调控。一些细胞核内的合成可能是核糖体对新合成的RNA进行错误放置的终止密码子校对（一个触发“无义介导的衰变”的过程）的副产物。我们推测一些“暗物质”肽将在细胞中发挥其他重要作用。
