A pseudoatomic model of the C. thermophilum Vps1 assembly. (A) The building blocks used to assemble the pseudoatomic model: the Vps1 GG_GMPPCP dimer and the stalk domain dimer from rat dynamin 1 ΔPRD. (B) Assembled pseudoatomic structure generated by sequential docking and application of the refined helical parameters for the Vps1 GG_GMPPCP dimer and the stalk dimer. The fit of each of the positioned dimers was subsequently locally refined. (C) As for B but shown without the density from the reconstruction. (D) End-on view of the pseudoatomic model overlaid with the density. The protrusion of unfilled density facing the lumen of the helix, likely occupied by the start and end of Insert B, is indicated. (E) Assembly Interfaces 1 and 3 form between adjacent dimers at the stalk region (inner density layer). Four stalk dimers are shown. (F and G) Detail of the Vps1 assembly interfaces. (F) The fit of the pseudoatomic model showing two adjacent dimers within the Vps1 helical assembly, showing the canonical GG GTPase interface and the novel αB interface between neighboring GTPase domains. The C_GED helix, which directly connects to the linker at its C terminus, is labeled. (G) The αB interface, circled in red, is formed by the αB and the β2A–αB loops from related GTPases.