Patterns of average base composition around polyadenylation [poly(A)] sites in fungi, plants, and animals. Sequence logo (seqlogo) graphs were drawn based on the average base composition among mapped poly(A) sites. Position 31 in these seqlogo graphs is the poly(A) tail starting position (corresponding to position 1 in Figure 5). Position 30 in these seqlogo graphs is the poly(A) tail attachment position (corresponding to position −1 in Figure 5). Positions 13 and 22 in these seqlogo graphs correspond to positions −18 and −9 in Figure 5. Note that the base composition pattern was highly conserved among the fungal, plant, and animal kingdoms. In the U-A-U-A-U pattern, the first U was the relatively far-upstream U-rich region (1st UUR), the first A was the upstream A-rich region (UAR), the second U was the upstream U-rich region (2nd UUR), the second A was the A at the poly(A) site (SiteA), and the last U was the downstream U-rich region (DUR). The 70-base segment upstream of this seqlogo region was U-rich in fungi, plants, and animals (partly shown in Figure 5).