Table 1.
Class Ib residues at conserved positions involved in MHC class Ia terminal peptide anchoring.
| Class Ib: XNC/SNC | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| HLA-A2 | CD1d | Xl Class Ia | MR1 | CLUSTER 1a | CLUSTER 2a | CLUSTER 3a | CLUSTER 4a | CLUSTER 5a | CLUSTER 6a | CLUSTER 7a | |
| A pocket | Tyr7 | Cys | - | - | - | -/Phe (Leu/Val) | - (Phe) | - | -/Leu | - (Phe) | - |
| Tyr59 | Gln | - | His | Leu/His/Asp/Asn | Met (Ile) | His(Glu) | His | His (Leu) | His (-) | Ala | |
| Tyr159 | Leu | - | Trp | - | -/Phe | Phe (Leu/Ser) | - | - (Asn) | Phe/- | - | |
| Trp167 | Phe | Gly | - | His (Gly) | Arg | His | His (Tyr) | His/Gln (Asn/Tyr) | His (Asn) | Asp | |
| Tyr171 | Leu | - | Phe | - (His) | - (Phe) | - (Phe) | - | - | - | - | |
| F pocket | Arg/Tyr84 | Met | - | His | Ser | Ile/Leu | Leu/(Ser) | Phe | Phe/Tyr | Val/Phe | Met |
| Thr143 | Ala, Pro | - | Thr/Ile | Ala (Val) | Val (Ile/Ala) | Leu | Leu/Met | Met (Val/Ile) | Val (Leu/Met) | Val | |
| Lys146 | Val | - | Ala | Arg/- | Ile (Val/Leu) | GAP | Ser/Arg/Glu/Gln | Gln (leu) | Leu | Gln | |
| Trp147 | Leu | - | Trp | - (Arg) | - | - | - | - | - | Cys | |
| Ligand | peptides | lipids | vitamin B metabolites | ||||||||
Putative ligand binding residues of Xenopus/Siluriana class Ia and class Ib where predicted based on alignment with human HLA-A.
a
Cluster refers to phylogenetically related families of XNC/SNC sequences.
- conservation of residue with MHC class Ia; GAP, gap in the sequence such that no equivalent residue is determined.
Bold, unique residue among the differnet XNC/SNC molecules. x/x, equal distribution of two different amino acids (x) amino acid only detected in 1–2 of sequences in the group.
Grey shade, hydrophobic amino acids