Fig. 1.

Comparison of homologous subunits between MBH, Complex I and Mrp antiporter. Nqo numbers are given for each T. thermophilus complex I subunit with the correlated Nuo letter in parenthesis. Red subunits represent the catalytic subunits and include mbhL and nuoD. Orange subunits represent the Q module and include mbhJKLN and nuoBCDI. Aqua colored subunits are homologous and include mbhH, nuoLMN, and mrpAD. Blue subunits are homologs to mbhM and include nuoH. Light green subunits are homologous to mbhG and include mrpC. Green subunits are homologous to mbhABC and include mrpEFG. Gray subunits are homologous to mbhDEF and include mrpB. Yellow subunits represent the N module of Complex I and include nuoEFG. MbhI is shown in brown and the dark blue subunits represent nuoAJK. Tan subunits represent two subunits that were observed in the 16-subunit crystal structure of Nqo from T. thermophiles (Efremov et al., 2010). There is no homology between the three complexes for mbhI, nuoAEFGJK or Nqo15–16. Fd_red and Fd_ox represent reduced and oxidized ferredoxin, respectively, and QH₂ and Q represent reduced and oxidized ubiquionone, respectively.