Frequency of occurrence of specific class 2 and 3 PDZ ligand motifs in the cytoplasmic domains of 99 MHCI proteins from 21 species. A. Class 2 PDZ ligand motifs ([ΦXΦ], where Φ = V, I, L, M, F, W, or C), or B. class 3 PDZ ligand motifs ([D/E X Φ) [46]) in the cytoplasmic domains of 99 MHCI proteins from 21 species (data used to create pie charts in Fig. 2e and f, respectively). Shown are the number of occurrences of each motif as well as the fraction they represent of the total motifs observed in each domain. Class 2 PDZ ligand forms that were never observed in either domain are not shown. (PPTX 73 kb
