Curanovic, D. et al. Nat. Chem. Biol. doi:10.1038/nchembio.1334 (1 September 2013).

Extracellular signaling molecules can promote translation by inducing polyadenylation, the addition of a poly(A) tail to mRNA. However, current methods cannot distinguish between mRNA molecules polyadenylated as a result of an external stimulus and those with preexisting poly(A) tails. In order to specifically identify those transcripts polyadenylated in response to a stimulus, Curanovic et al. synthesized an adenosine analog that is selectively incorporated into poly(A) tails. This alkyne-containing analog is incorporated into RNA by the existing machinery in living cells, allowing click-chemistry–based purification. The researchers used deep sequencing to identify 1,737 transcripts polyadenylated in oocytes in response to progesterone treatment, which activates oocyte maturation. This tool and method allowed them to perform an in-depth investigation of RNA sequence motifs associated with polyadenylation.