Extended Data Fig. 3. Example regions of the density map with the model fitted to the map.

a) ND2 is shown from the membrane plane, high-lighting the densities for three aromatic sidechains and one of the helix-breaking loops. b) Subunit ND4 is viewed from the matrix. c) The density for a [4Fe-4S] cluster and surrounding protein is shown in the PSST subunit. d) A region of the 49 kDa subunit shows a well resolved α-helical stretch and aromatic side-chains, and the β-strands are beginning to be resolved. e) Subunit B8 is an example of a supernumerary subunit in a peripheral region of the molecule. f) In the 39 kDa subunit density consistent with a bound nucleotide is observed, in a similar position to in homologous structures, and as expected from analysis of Y. lipolytica complex I²⁷. However, the present resolution of the map precludes the inclusion of this nucleotide in the final model.