Figure 4. Landscape of AS events in the 5′ UTR vs. CDS.

Landscape of AS events in RefSeq with all variable splice sites included in the 5′ UTR (A) in comparison to the ones included in the genomic region of the CDS (B). The structurally different groups are colored as in Figure 3. ES is more frequent in the CDS, whereas IR is observed more often in the 5′ UTR. Whereas in CDS alternative acceptors are more frequent than alternative donors, the landscape of events in the 5′ UTR exhibits a reverse ratio with a bias against alternative acceptors. The more complex AS events are mainly located in the region of the CDS.