Table 3.
Prevalence of codons critical for the emergence of Ca2+ binding sites in splicing regulatory hexamers
| Amino acid | E (Glu) | E (Glu) | D (Asp) | D (Asp) | |
|---|---|---|---|---|---|
| Codon | GAA | GAG | GAC | GAU | Total |
| ESEs (n = 1182)a | 146 (0.43) | 105 (0.37) | 177 (0.49) | 113 (0.38) | 541 |
| ESSs (n = 1090)a | 10 (−0.37) | 32 (−0.30) | 7 (−0.34) | 23 (−0.41) | 72 |
| Fold excess of codon frequencies in ESE over ESSb | 13.5 | 3.1 | 23.3 | 4.5 |
aHexamers and their ESEseq and ESSseq scores were reported previously (60). The scores represent quantitative measures of splicing activities of exon hexamers (60). Mean ESEseq or ESSseq scores of hexamers containing the indicated codons are in parentheses.
bFrequencies were computed for 4728 codons in ESEs and 4360 codons in ESSs. Predicted splicing activities of all sense and nonsense codons are shown in Figure 10A and Supplementary Figure S18.