2-Ethynyl-adenosine

2-Ethynyl-labeled adenosine (2-EA) can be used to measure de novo mRNA poly (A) tail synthesis in proliferating cells. 2-EA is cell permeable and incorporates into nascent mRNA transcripts both transcriptionally by RNA polymerase I, II and III and posttranscription-ally by poly (A) polymerase instead of their natural analolg adenosine. The resulting ethynyl-functionalized RNA can subsequently be detected via Cu (I) -catalyzed click chemistry that offers the choice to introduce a Biotin group (via Azides of Biotin) for subsequent purification tasks or a fluorescent group (via Azides of fluorescent dyes) for subsequent microscopic imaging.