The end of the message: multiple protein–RNA interactions define the mRNA polyadenylation site

The key RNA sequence elements and protein factors necessary for 3' processing of polyadenylated mRNA precursors are well known. Recent studies, however, have significantly reshaped current models for the protein-RNA interactions involved in poly(A) site recognition, painting a picture more complex than previously envisioned and also providing new insights into regulation of this important step in gene expression. Here we review the recent advances in this area and provide a perspective for future studies.