Fig. 2.

Atomistic model of the MHC-I peptide-loading complex. (A) The 1.6-million-atom molecular dynamics simulation system contains the complete human MHC-I PLC (75.939 atoms), embedded in a POPC lipid bilayer (101.036 atoms) and solvated by explicit water with Na⁺ and Cl⁻ ions. (Only a small slab of water is shown for clarity.) (B) The PLC model was built by fitting atomistic subunit structures to the cryo-EM density for a single editing module (EMD-3906) (5) and then duplicating this module and fitting to the cryo-EM data (EMD-3094) (5) for the pseudosymmetric assembly (cryo-EM density for a single module shown as a surface).