Derti, A., et al. Genome Res. advance online publication (18 April 2012).

Alternative polyadenylation (poly(A)) adds to transcript variety as several sites within the 3′ UTR of a transcript can be chosen as recipients of the poly(A) tail. Some of these alternative poly(A) sites are important for normal development and disease; this prompted researchers to develop high-throughput methods to detail all poly(A) occurrences in the transcriptome. The PolyA-seq approach of Derti et al. captures the sequence immediately upstream of the poly(A) tail in a strand-specific and quantitative manner. Through their analysis of 24 tissues in five mammalian species, the researchers increased the number of known poly(A) sites in human cells by over 50% and showed that almost 70% of human genes have more than one poly(A) site in their 3′ UTR. This vast catalog of poly(A) sites will provide insight into evolutionary conservation of sites and provide a rich resource for studying the tissue-specific functions of alternative polyadenylation.