Qualitative imaging of biomolecular localization and distribution inside cells has revolutionized cell biology. Most of these powerful techniques require modifications to the target biomolecule. Over the past 10 years, these techniques have been extended to quantitative measurements, from in-cell protein folding rates to complex dissociation constants to RNA lifetimes. Such measurements can be affected even when a target molecule is just mildly perturbed by its labels. Here, the impact of labeling on protein (and RNA) structure, stability, and function in cells is discussed via practical examples from the recent literature. General guidelines for selecting and validating modification sites are provided to bring the best from cell biology and imaging to quantitative biophysical experiments inside cells.

中文翻译：

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用于体外和细胞内成像测量定量比较的标签

细胞内生物分子定位和分布的定性成像彻底改变了细胞生物学。这些强大的技术大多数都需要对目标生物分子进行修饰。在过去的10年中，这些技术已扩展到定量测量，从细胞内蛋白质折叠速率到复杂的解离常数再到RNA寿命。即使目标分子仅受到其标记的轻微干扰，此类测量也会受到影响。在这里，通过最近的文献中的实例讨论了标记对细胞中蛋白质（和RNA）结构，稳定性和功能的影响。提供了选择和验证修饰位点的一般指南，以使从细胞生物学和影像学到细胞内定量生物物理实验的最佳过程。