(A). The N-terminal end-on view, the side, and the rotated side view of single CMG.
(B). The side view of a double CMG in a configuration distinct from what was previously observed with the yeast CMG assembled at an origin of replication.
(C) A view of the MCM ATPase improved after focused classification and refinement.
(D) Unassigned density after building the double CMG atomic model.
(E) Cartoon representation of a DONSON homodimer built into the cryo-EM density represented with transparent surface rendering and a cut-through view.
(F) Mass photometry analysis demonstrates that purified recombinant DONSON homodimerizes.