Table II. Polarity and size of C-terminal residues among HLA-B27 subtype-bound peptides. The nature of residue 116 in each subtype is indicated. Figures are residue frequencies (%) among the peptides sequenced from the corresponding subtype. Values selectively increased in a subtype group are highlighted in boldface. For the statistical significance of the differences in residue usage among subtypes in the C-terminal position see supplemental Table S6.
| B*27:02 (D116) | B*27:03 (D116) | B*27:04 (D116) | B*27:05 (D116) | B*27:06 (Y116) | B*27:07 (Y116) | B*27:09 (H116) | |
|---|---|---|---|---|---|---|---|
| POLARITY | |||||||
| Basic | 2.1 | 21.9 | 4.5 | 17.4 | 1.6 | 1.8 | 3.1 |
| Non-polar Aliphatic | 35.2 | 37.1 | 50.2 | 41.6 | 78.7 | 67.9 | 74.0 |
| Non-polar Aromatic (F) | 29.8 | 17.2 | 22.4 | 21.9 | 15.4 | 27.0 | 19.3 |
| Polar Aromatic (Y) | 30.1 | 21.5 | 21.0 | 17.7 | 2.4 | 2.1 | 1.9 |
| SIZE (Da) | |||||||
| 57–103 | 2.5 | 7.0 | 10.4 | 6.9 | 13.9 | 9.6 | 9.6 |
| 104–115 | 30.3 | 26.3 | 37.4 | 30.4 | 63.7 | 52.1 | 58.6 |
| 116–137 | 4.6 | 17.2 | 6.6 | 14.2 | 4.2 | 8.4 | 9.3 |
| 138–186 | 62.6 | 49.6 | 45.6 | 48.4 | 18.3 | 30.0 | 22.5 |