Extended Data Fig. 6: Mgm1 tetramers in crystal and membrane lattices.

a–d, Mgm1 assemblies in the presence of GTPγS on the outer (a, c) and inner surface (b, d) of a membrane tube. a, b, Surface representations of flexibly fitted Mgm1 molecules, showing their arrangement in the protein lattice. c, d, Fit into the corresponding cryo-ET volume. Note that the membrane density and, consequently, the paddle–membrane contact, is more prominent in the GTPγS-bound form compared with the nucleotide-free form (Figs. 4b, 5a). e, Comparison of Mgm1 tetramers in the crystal lattice (blue) with tetramers fitted to the subtomogram average volumes obtained for the external (orange) and internal surface lattice (pink). Fitting the paddle and the BSE and G domains required only minor rearrangements. f, Tetramers in the crystal lattice pack into a linear assembly. Crystal contacts between two tetramers are mediated by the BSE domain of one tetramer (blue) and the stalk domain of the neighbouring tetramer (grey), resulting in an open interface-1. When comparing intra- and inter-tetramer interactions, BSE domain residues E533, E534 and Y537 in α2^B bind to different sites of the adjacent stalks.