Figure 2. Evolutionarily conserved MHC class Ib₁₁₂ among lower vertebrates.

a) Alignment of the class Ib₁₁₂ genes from Xenopus and reptiles. Dots show residues identical to X. tropicalis 112. Dashes show deletions. *, 8, and b denote peptide-binding residues that are evolutionary conserved among classical class Ia, CD8 binding sites, and beta-2 microglobulin binding sites, respectively. Typical conserved amino acid residues for IgSF domains are highlighted in blue. GenBank accession numbers (obtained from ncbi.nlm.nih.gov) of the class Ib₁₁₂: Chmy (Chelonia mydas: Green sea Turtle) XP_007069382; Pesi (Pelodiscus sinensis: Chinese soft-shell turtle) XP_014430793, XP_006126776; XP_014430792, XP_014430791, XP_014430790, XP_014430790; Chpib (Chrysemys picta bellii: painted turtle) XP_005313900, XP_008175642; Alsi (Alligator sinensis: Chinese Alligator) XP_006037953; Almi (Alligator mississippiensis: American Alligator) XP_019343116.

b) Conserved synteny of class Ib₁₁₂ in amphibians and reptiles. Each box indicates a single gene. Red boxes represent the 112 class Ib genes: The number of genes varies depending on the species, and these genes could only be found in amphibian and reptiles. Data were retrieved from NCBI (www.ncbi.nlm.nih.gov/gene/).