Extended Data Fig. 4: Conformations of the I + III₂ supercomplex in different species.

Comparison of I + III₂ supercomplex from Arabidopsis, Tetrahymena and ovine mitochondria. Atomic models of complex I are blue, complex III₂ is red. The position of the inner mitochondrial membrane is indicated by the detergent micelles in the cryo-EM maps lowpass-filtered to 7 Å (grey). Left: conformation 2 of Arabidopsis thaliana; centre: consensus refinement of Tetrahymena thermophila; right: open conformation of Ovis aries. a, View from the tip of the complex I membrane arm, indicating the angle to which the membrane around complex III₂ bends relative to complex I. The different angles in conformation 1 in Arabidopsis and the closed conformation of the ovine supercomplex are indicated by grey lines. b, Angle included between complex III₂ and the complex I membrane arm as seen from the mitochondrial matrix. The dotted line indicates the approximate long axis of the complex I membrane; the straight black line is the transverse axis of complex III₂. Grey lines indicate the transverse axis of Arabidopsis conformation 1 and the ovine closed conformation. The Arabidopsis structure is from this study, the structure of the open Ovis aries supercomplex is from²⁵ (PDB: 6QC3, EMDB: 4495) and that of the Tetrahymena supercomplex from¹⁶ (PDB: 7TGH, EMDB: 25882).