|  | Human |  | Mouse |  |
---|
 |  | Obs | Exp | Obs | Exp |
---|
ATG | ALT | 10.2 | 12.9 | 10.4 | 13 |
 | CONSTIT | 7.9 | 12.4 | 8.6 | 12.7 |
AGT/GTA/GAT/TAG/TGA | ALT | 60.9 | 64.5 | 65.8 | 65.0 |
 |  | (12.1) | (12.9) | (13.2) | (13.0) |
 | CONSTIT | 58.7 | 62.0 | 63.7 | 63.5 |
 |  | (11.7) | (12.4) | (12.8) | (12.7) |
- Observed and expected frequencies of AUG triplets (top tier) and shuffled triplets (AGT/GTA/GAT/TAG/TGA) that are permutations of AUG (bottom tier), per 1000 nucleotides in ALT and CONSTIT regions of 5'UTR. The significance of the differences between expected and observed frequencies of uAUG and shuffled triplets was estimated using the χ2 test. All comparisons using the χ2 test are highly significant (P < 10-10) except for two cases in mouse: observed ALT_AGT/GTA/GAT/TAG/TGA versus expected ALT_AGT/GTA/GAT/TAG/TGA (P = 0.41) and observed CONSTIT_AGT/GTA/GAT/TAG/TGA versus expected CONSTIT_AGT/GTA/GAT/TAG/TGA (P = 0.97).