Polyadenylation of mRNA is a key step in post-transcriptional regulation. In this issue of Genes & Development , Gabs and colleagues (doi:10.1101/gad.352912.125) provide evidence for a novel, kinetically driven mechanism that dictates the length of poly(A) tails added to mRNAs in budding yeast. The investigators introduce the concept of Nab2, a zinc finger poly(A) RNA binding protein, as a “kinetic ruler,” which functions through dynamic competition with the cleavage and polyadenylation complex (CPAC) to define the length of poly(A) tails.
Anita H. Corbett (Tue,) studied this question.