Figure 9. Transmembrane topology model of the NDH-F polypeptide.

Hydrophobic helices are labelled with roman numerals and hydrophilic regions are labelled with lower-case letters, according to the PHD model (see Figure 4). The net charge of hydrophilic regions is indicated within parentheses. The length of all transmembrane helices was 18 amino acids, except in IV, XI and XV, which have 20 amino acids, and XIII, which has 19 amino acids. The conserved Thr-181 (phosphorylation site) and His-349 (for H⁺ translocation) are indicated.