Figure 1. Distribution of conserved splice sites of real introns in six organisms. In these logo graphs, the information content ranges from zero to two. Zero signifies no conservation (all four nucleotides have equal probability of use) and two indicates the maximum degree of conservation (one nucleotide is present).

Figure 2. Example of a pseudoexon, formed in intron 6 between exons 6 and 7 (open boxes) of the human gene encoding the growth-hormone receptor (GHR): the pseudoexon sequence (6) is located between the bar signs (‘|’) and is indicated in bold. Underlined letters indicate the base that when mutated activates the pseudoexon, which leads to pathological insensitivity to growth hormone. The mRNAs for both normal and mutant genes are shown above the genes (thick lines indicate exons in mature mRNAs).