Structural Mechanism of ER Retrieval of MHC Class I by Cowpox
Figure 3
Crystal structure of CPXV203 bound to MHCI.
(A) Ribbon diagram of the complex structure of CPXV203 (magenta), Kb (blue), β2m (grey), and OVA257–264 (yellow, spheres). No N-linked glycosylation sites are present near the interface. Membrane proximal domain shifts, α3 (7.2°) and β2m (16.8°), are within the range observed in previous crystal structures of free MHCI (see Text S1). (B) Comparison of CPXV203/MHCI binding orientation to other MHCI binders: viral (US2) [25], chaperone (Tpn), co-stimulatory (CD8αα) [35], and NK receptor (Ly49C) [40]. Chains colored as in A. Proposed Tpn contact loops (α2 128–136, α3 222–229) are colored magenta with contacts identified by mutagenesis shown as spheres [36],[37],[39],[52]. See also Table S2 and Figure S2.