Table S1.

Comparison of EI^{partially closed} and EI^closed structures

Structure comparison	Cα atomic rms difference, Å	Rotation, °	Centroid translation, Å
Comparison of EIpartially closed vs. EIclosed*
EINα relative to EINα/β	6.2 ± 0.4/2.9 ± 0.3	11.1 ± 0.7/9.4 ± 0.8	5.9 ± 0.3/2.2 ± 0.3
EINα/β relative to EIC	7.5 ± 0.2/6.9 ± 0.1	16.5 ± 0.6/13.8 ± 0.5	6.7 ± 0.1/6.2 ± 0.1
EIN relative to EIC	16.1 ± 0.2/15.8 ± 0.2	23.1 ± 0.2/15.8 ± 0.2	13.7 ± 0.2/10.9 ± 0.2
Comparison between the two subunits of EIclosed
EINα relative to EINα/β	5.6	5.4	5.5

In this series of comparisons, the differences in the positions of EIN^α, EIN^α/β, and EIN between the EI^{partially closed} and EI^closed structures are characterized in terms of C^α rms difference as well as rotation and translation between centroids, computed by best-fitting to EIN^α/β, EIC, and EIC, respectively.

^*First and second numbers refer to subunits A and B, respectively, of EI^closed. In EI^closed, the EIN^α subdomains are asymmetrically placed relative to the C₂ symmetry axis of the EI^α/β-EIC dimer, as a consequence of asymmetric EIN^α intersubunit contacts (14). The average C^α rms differences for EIN alone between the top 10 EI^{partially closed} structures and subunits A and B of EI^closed are 1.5 ± 0.1 and 1.1 ± 0.1 Å, respectively.