Figure 11. Sequence alignment of cytochromes c1 with other class I cytochromes. The alignment of cytochromes c1 (1BCC), c (1HRC, 1YCC), c2 (1C2R), c6 (1CYI), and c8 (351C) are based on superimposed structures from the indicated PDB entries. The other cytochromes c1 for which no structure is available were aligned by conventional sequence alignment. Boxed regions of the sequence indicate the 3 conserved helices 1, 3, and 5; helices 2 and 4 in cytochromes c and c2; helix 2' in cytochrome c1; and the heme-bracing PXL tripeptide. Highly conserved residues are indicated in bold type. The sequence numbering of horse cytochrome c is indicated at the top, and that for bovine cytochrome c1 at the bottom.