Table 7. Frequent CPs common to aaRSs and birA.
| CP (alternatives) | Structural properties | # of birA occurrences | # of aaRSs occurrences | # of class I occurrences | # of class II occurrences |
| GILIE(GILVEGILTE) | Biotin binding site in birA,ThrAMS binding site in ThrRS | 198 | 2 | 2 | 113 |
| GALRL(GALLL) | Binding site for 4AD in AspRS | 32 | 1 | 0 | 42 |
| GEALG(GETLG) | Helix-turn-Helix in birA | 22 | 4 | 1 | 31 |
| LRAAL | α-helix in birA | 86 | 13 | 43 | 7 |
*Alternatives in brackets mark one-mutation-distant CPs that were selected on birA but not in aaRSs.
4AD = 4-Amino-1,4-Dioxobutan-2-Aminium Adenosine- 5′-Monophosphate.