Figure 3. Functional and structural equivalence of the SCT constructs and native H2-K^b-Ova.

(a) The peptide-binding platforms of SCT^WT, gray; SCT^Y84A, yellow; dt-SCT, magenta are superposed onto the platform of native K^b-Ova, cyan. The superposition is based on the overlap of the main chain atoms of HC residues 1 through 182. The superposed structures are depicted as ribbon tubes. Side chains for Ova residues in each SCT and in the native complex are rendered as ball and stick models and colored correspondingly. (b) Response of OT-1 T cells to LM1.8 cells transfected with K^b and fed 10 µM Ova (panel 1, cyan); or transfected with SCT^WT (panel 2, gray), SCT^Y84A (panel 3, yellow), and dt-SCT (panel 4, magenta) is compared to the OT-1 response to control LM1.8 transfectants (H2-K^b, no peptide, shown in red in each panel) in a ⁵¹Cr release assay. (c) and (d) The Ova atomic positions in each SCT are compared to the native peptide. A close-up view of the superposed Ova peptides is shown at a near 90° rotation from the orientation in (a). Aligned underneath the peptides (d) are quantified positional differences, which were graphed to denote per residue main chain (top) and side chain (bottom) differences in reference to native Ova.