Tales of Detailed Poly(A) Tails.

Poly(A) tails are non-templated additions of adenosines at the 3' ends of most eukaryotic mRNAs. In the nucleus, these RNAs are co-transcriptionally cleaved at a poly(A) site and then polyadenylated before being exported to the cytoplasm. In the cytoplasm, poly(A) tails play pivotal roles in the translation and stability of the mRNA.

Short poly(A) tails are a conserved feature of highly expressed genes.

Poly(A) tails are important elements in mRNA translation and stability, although recent genome-wide studies have concluded that poly(A) tail length is generally not associated with translational efficiency in nonembryonic cells. To investigate whether poly(A) tail size might be coupled to gene expression in an intact organism, we used an adapted TAIL-seq protocol to measure poly(A) tails in Caenorhabditis elegans. Surprisingly, we found that well-expressed transcripts contain relatively short, well-defined tails.