Natural selection targeted the CD94/NKG2 residues interacting with the peptide presented by MHC class I ligands in “lower” primates.

Binomial test to investigate whether positively selected residues are randomly distributed or are clustered at functionally relevant sites of the molecules. Several CD94/NKG2 functional categories were considered based on the human CD94/NKG2A crystal structure [22],[23]: residues contacting the peptide presented by the MHC ligand form the ‘Peptide’ category while those contacting the MHC class I heavy chain form the ‘MHC’ category; residues mediating heterodimer formation represent the ‘Dimer’ category. Additionally, Peptide and MHC contacts (‘Ligand binding’) and all known contact residues (‘All’) are summarised. Details on the residues in each category are in Figure S6.