方法指南：细胞增殖和细胞活性检测方法指南（点击查看/下载）PDF

5-Ethynyl uridine (EU) is a novel alternative for bromo uridine (BrU or BrUTP) to directly image spatially and temporally nascent global RNA transcription both in vitro and in vivo. EU is a nucleoside analog of uracil, and is incorporated into RNA during active RNA synthesis.

Detection of the incorporated EU is based on a powerful click chemical reaction that utilizes bio-orthogonal moieties, specifically azides and alkynes. EU contains an alkyne that can react with an azide-containing detection reagent to form a stable triazole ring. Because click chemistry-based label and detection tags react selectively and specifically with one another, you can apply click-labeled molecules to complex biological samples and subsequently detect with unprecedented sensitivity due to an extremely low background.

It has been demonstrated that EU can be efficiently incorporated into RNA by several polymerases, but it does not incorporate into DNA.