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Figure 3.
Figure 3. (a) Superposition of peptides bound to
human MHC class II molecules. The MBP 86-105 pep-
tide bound to HLA-DR2a is red and the MBP 85-99 pep-
tide bound to HLA-DR2b (Smith et al., 1998) is green. In
yellow are peptides bound to other HLA-DR molecules:
DR1 (Stern et al., 1994), DR3 (Ghosh et al., 1995) and
DR4 (Dessen et al., 1997). HLA-DR2a is shown in gray.
The peptide backbones superpose well from P-2 to P4,
but display considerable divergence beginning at P6. In
particular, the C-terminal portions of the MBP peptides
presented by DR2a and DR2b are positioned higher in
the binding groove than the C-terminal portions of pep-
tides presented by DR1, DR3, or DR4. (b) Confor-
mations of Trp61b in HLA-DR2a and HLA-DR3. In red
are the MBP peptide bound to HLA-DR2a and the side-
chains of residues Trp61b and Leu38b of this DR. In yel-
low are CLIP peptide bound to HLA-DR3 (Ghosh et al.,
1995) and the side-chains of Trp61b and Val38b. HLA-
DR2a and HLA-DR3 are gray and blue, respectively.
Superpositions were done using the a1 and b1 domains
of the DR molecules.
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