The Emergence of Alternative 3′ and 5′ Splice Site Exons from Constitutive Exons
Figure 3
Alignment of flanking intron regions was performed using the local alignment program Sim4 for upstream and downstream flanking intron (left and right panel, respectively). The x-axis represents the identity length (bp) and the y-axis represents the percentage of introns that were found to have an identity in that length or higher.
(A) Conservation level of flanking introns for constitutive (blue circle), cassette (pink square), alt 3′ss (light blue diamond), and alt 5′ss (dark red triangle) exons.
(B) Conservation analysis combined with division of the A3Es and A5Es into two subgroups according to their extension length (8 bp and less versus 9 bp and more). Analysis for the two subgroups is presented for the upstream intron of A3Es (light blue and light green diamonds) and for the downstream intron of A5Es (dark red and light green triangles).