Figure 1.

Donor and acceptor sites' pictograms. Pictograms of the donor (left) and the acceptor (right) site sequences for the U2 (top) and U12 (bottom) splice sites. The sequence plots for GT-AG and GC-AG U2 introns are given separately. The conserved sequence of the U12 branch point is also shown. From human, mouse, rat, and chicken RefSeq genes, a total number of 337,336, 2506, and 935 splice-site sequences from CDS introns from Ensembl were included in GT-AG, GC-AG, and U12 splice site sets, respectively, to produce the corresponding pictograms.