Table 2. Characterization of natural amino acid variation for each residue identified under positive selection in primate IgA.
| Natural amino acid variation | ||||||
| Residuea | Functional information | H, +b | H, - b | H, n b | HY, n b | |
| Primates Cα1 | ||||||
| 133 | Close to hinge | K | D, E | – | C | |
| 166 | Exposed | R, K, H | – | S, Q, T | P, I, L | |
| Primates Cα2 | ||||||
| 296 | Exposed | R, H | – | – | – | |
| 319 | Exposed; close to SSL7 binding site | K | E | Q | V | |
| 326 | Exposed | – | E | N | A | |
a
IgA1 Bur numbering.
b
amino acid characteristics: H- Hydrophilic, HY- Hydrophobic, +- positive, –negative, n-neutral.