Abstract
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 whether this has any functional significance is poorly understood. Using hierarchical clustering of 3' UTRs, we identify eight classes of S. cerevisiae genes based on their poly(A) site locations. Genes involved in related biological functions (GO categories) are uniquely over-represented in six of these classes. Similar analysis of S. pombe genes reveals three classes of 3' UTRs, all of which show over-representation of functionally related genes. Remarkably, S. cerevisiae and S. pombe homologs share related patterns of poly(A) site locations. These observations suggest that the location of poly(A) sites within 3' UTRs has biological significance.