Table 3.
Observed cases of U2 subtype switching within mammals
| (A) Orthologous pairs
| ||||
|---|---|---|---|---|
| GT, GT | GC, GC | GC, GT | GT, GC | |
| human/mouse | 38,922 | 190 | 100 | 99 |
| human/rat | 11,693 | 61 | 33 | 23 |
| mouse/rat | 8441 | 60 | 8 | 7 |
| (B) Orthologous triads
| ||||||
|---|---|---|---|---|---|---|
| Human | Mouse | Rat | Occurrences | |||
| “ancient” GT-AG | ||||||
| GT | GT | GT | 7784 | |||
| “ancient” GC-AG | ||||||
| GC | GC | GC | 45 | |||
| “moderate” GC-AG | ||||||
| GC | GT | GT | 23 | |||
| GT | GC | GC | 11 | |||
| “recent” GC-AG | ||||||
| GT | GT | GC | 8 | |||
| GT | GC | GT | 5 | |||
| “ancient” GC-AG, “recent” GC → GT | ||||||
| GC | GC | GT | 2 | |||
| GC | GT | GC | 1 | |||
| Total | 95 | |||||
(A) Orthologous pairs: occurrence of donor site dinucleotide pairs at intron boundaries of orthologous intron pairs. For instance, we have found 65 instances in which the orthologous donor site is GC in human and GT in mouse.
(B) Orthologous triads: occurrence of donor site dinucleotides at intron boundaries in orthologous intron triads. For instance, we have found 23 cases in which the donor site is GC in human, but GT in both mouse and rat.