Figure 5.

The HSPD1 inverted double ring

(A) Selected 2D classes of the inverted double ring.

(B) D7-symmetrical reconstruction of the inverted double ring with one ring colored by subunit and the second ring in gray. The interface between the two rings is highlighted by the white rectangle.

(C) Magnified view of the inter-ring interface of the double ring with potential interacting residues labeled.

(D) Schematic of the HSPD1 oligomeric states, apo GroEL, and HSPD1/HSPE1 complexes in comparison. Depicted are central sections of side views for the complexes. The eighth subunit is not resolved by cryo-EM, thus probably disordered, and has been placed in the substrate binding site on the apical domains. According to native MS data, the inverted double ring may contain one or two additional (unresolved) subunits.