Fig. 2.

Cardiolipin binding to Aac2p. (A) Schematic representation of the key elements of the cardiolipin-binding sites. The even-numbered and matrix helices for one binding site are shown as cylinders, with a rainbow color scheme (N terminus, blue; C terminus, red), the linker helix is shown in cyan. (B) Detailed view of the binding site for cardiolipin (Cdl801 in chain A of the P2₁2₁2₁ crystal form). Residues in the linker helix, even-numbered helix, and matrix helix are shown with cyan, yellow, and blue carbon atoms, respectively. Hydrogen bonds within these helices are shown as thin black-dotted lines. Residues in the [YWF][KR]G and [YF]xG motifs are shown in violet and green, respectively. Residues contacting cardiolipin are shown with spheres. Hydrogen-bond interactions between protein and cardiolipin are shown as thick black-dashed lines. Electron density is present for only part of the cardiolipin acyl chains, and they have therefore been modeled with truncated acyl chains.