Location of polyadenylation sites within 3' untranslated regions is linked to biological function in yeast

Expression of a typical yeast gene results in ~50 3' mRNA isoforms that are distinguished by the locations of poly(A) sites within the 3' untranslated regions (3' UTRs).The location of poly(A) sites with respect to the translational termination codon varies considerably among genes, but it is unknown whether this has any functional significance.Using hierarchical clustering of 3' UTRs, we identify eight classes ofS. cerevisiaegenes based on their poly(A) site locations within 3' UTRs.Genes involved in related biological functions (GO categories) are uniquely over-represented in six of these classes.Similar analysis ofS. pombegenes reveals three classes of 3' UTRs, all of which show over-representation of functionally related genes.Remarkably,S. cerevisiaeandS. pombehomologs have similar patterns of poly(A) site locations.These observations suggest that the location of poly(A) sites within 3' UTRs has biological significance. Overall design: 3' READS to identify 3' isoforms (arising from alternative polyadenylation) of mRNA extracted from wild-type, exponentially growing S. pombe cells