Poly(A) tail dynamics: Measuring polyadenylation, deadenylation and poly(A) tail length.

Transcription of mRNAs culminates in RNA cleavage and a coordinated polyadenylation event at the 3' end. In its journey to be translated, the resulting transcript is under constant regulation by cap-binding proteins, miRNAs, and RNA binding proteins, including poly(A) binding proteins (PABPs). The interplay between all these factors determines whether nuclear or cytoplasmic exoribonucleases will gain access to and remove the poly(A) tail, which is so critical to the stability and translation capacity of the mRNA. In this chapter, we present an overview of two of the key features of the mRNA life-cycle: cleavage/polyadenylation and deadenylation, and describe biochemical assays that have been generated to study the activity of each of these enzymatic reactions. Finally, we also provide protocols to investigate mRNA's poly(A) length. The importance of these assays is highlighted by the dynamic and essential role the poly(A) tail length plays in controlling gene expression.