Fig. 3. Comparison of LBDs in GluK2_BPAM and GluK2_{Glu–ConA–BPAM}.

a,b, Single LBD in GluK2_BPAM (a; Protein Data Bank (PDB) ID: 8FWS) and GluK2_{Glu–ConA–BPAM} (b), with Glu shown as a space-filling model (green) and Cα atoms of S670 and P773 as blue and pink spheres, respectively. The 20° rotation of the lobe D2 towards D1 in GluK2_{Glu–ConA–BPAM} upon Glu binding is illustrated by the pink arrow. c,d, LBD dimers in GluK2_BPAM (c) and GluK2_{Glu–ConA–BPAM} (d), with BPAM shown as a space-filling model (dark blue) and the axes of the local two-fold rotational symmetry as continuous black lines. Distances between Cα atoms of S670 and P773 are indicated. e,f, Intracellular view of LBD tetramers in GluK2_BPAM (e) and GluK2_{Glu–ConA–BPAM} (f). The Cα atoms of S670 are connected by blue (e) or pink (f) lines and pink arrows illustrate the expansion forces applied to the M3–S2 linkers that induce channel opening.