Molecular dynamics simulations of the wild-type SecA–SecYEG and cross-linked SecA₇₉₅–Y₂₆₈EG complexes. Distances are between the centers of mass of the atoms comprising the groups of residues 791–799 (SecA) and 264–272 (SecY), respectively. Red is the wild-type (average: 7.81 ± 0.56 Å) and blue is SecA₇₉₅–Y₂₆₈EG cross-linked (average: 7.51 ± 0.28 Å). These statistical data were obtained from the single simulations shown here, which each represent an accumulation of force calculations for ∼570,000 atoms (50 million times for each trajectory).