Heme is essential for the survival of virtually all living systems—from bacteria, fungi, and yeast, through plants to animals. No eukaryote has been identified that can survive without heme. There are thousands of different proteins that require heme in order to function properly, and these are responsible for processes such as oxygen transport, electron transfer, oxidative stress response, respiration, and catalysis. Further to this, in the past few years, heme has been shown to have an important regulatory role in cells, in processes such as transcription, regulation of the circadian clock, and the gating of ion channels. To act in a regulatory capacity, heme needs to move from its place of synthesis (in mitochondria) to other locations in cells. But while there is detailed information on how the heme lifecycle begins (heme synthesis), and how it ends (heme degradation), what happens in between is largely a mystery. Here we summarize recent information on the quantification of heme in cells, and we present a discussion of a mechanistic framework that could meet the logistical challenge of heme distribution.

中文翻译：

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了解血红素在细胞中分布的物流

血红素对于几乎所有生命系统的生存都是必不可少的——从细菌、真菌和酵母，到植物到动物。没有鉴定出可以在没有血红素的情况下存活的真核生物。有成千上万种不同的蛋白质需要血红素才能正常发挥作用，这些蛋白质负责氧运输、电子转移、氧化应激反应、呼吸和催化等过程。此外，在过去几年中，血红素已被证明在细胞中具有重要的调节作用，包括转录、生物钟调节和离子通道门控等过程。为了发挥调节作用，血红素需要从其合成位置（在线粒体中）移动到细胞中的其他位置。但是虽然有关于血红素生命周期如何开始（血红素合成）的详细信息，以及它如何结束（血红素降解），两者之间发生的事情在很大程度上是个谜。在这里，我们总结了有关细胞中血红素定量的最新信息，并讨论了可以应对血红素分布后勤挑战的机制框架。