Figure 6.

Phylogenetic tree of MHC class II B genes from various vertebrate species. The tree was constructed by using p-distances for the amino acid sequences (188 residues) of domains β₁ and β₂. One allele from each locus was used as long as the locus was identifiable. In chicken and Xenopus the class II B loci have not been clearly identified, so that some sequences used may represent different alleles from the same locus. The human and mouse DM B genes, which are known to be distantly related to other class II B genes (31) were used as outgroups. The orthologous genes such as DQ, DP, etc., in different species are bracketed. M-rat, mole rat.