The diversity of ubiquitin modifications is immense. A protein can be monoubiquitylated, multi-monoubiquitylated, and polyubiquitylated with chains varying in size and shape. Ubiquitin itself can be adorned with other ubiquitin-like proteins and smaller functional groups. Considering different combinations of post-translational modifications can give rise to distinct biological outcomes, characterizing ubiquitylated proteoforms of a given protein is paramount. In this Opinion, we review recent advances in detecting and quantifying various ubiquitin proteoforms using mass spectrometry.

中文翻译：

---

泛素蛋白形式问题。

泛素修饰的多样性是巨大的。蛋白质可以是单泛素化、多单泛素化和多泛素化的，其链的大小和形状各不相同。泛素本身可以装饰有其他泛素样蛋白质和较小的官能团。考虑到翻译后修饰的不同组合会产生不同的生物学结果，因此表征给定蛋白质的泛素化蛋白形式至关重要。在本意见中，我们回顾了使用质谱法检测和量化各种泛素蛋白形式的最新进展。