Figure 1 - full size

 

Figure 1.
Figure 1. Structures of cyt b and ISP subunit in the bc[1] complex. A, Ribbon diagram of the dimeric cyt b and ISP in the bc[1] complex. Two cyt b subunits (labeled cyt b in light blue and cyt b-sym in green, respectively) and two ISP subunits (labeled ISP in yellow and ISP-sym in red, respectively) related by a molecular 2-fold symmetry are shown. The eight TM helices of cyt b are named sequentially from A to H. The two b-type hemes labeled b[L] and b[H] are shown as the ball-and-stick models. Two active sites in the cyt b are labeled: one is the quinone reduction site (Q[i]) and the other is the quinol oxidation site (Q[o]). The surface depression in cyt b on the inter-membrane space (IMS) side is labeled as the ISP-docking crater for interacting with the ISP. B, Stereo pair: structural environment of the native Q[o] site. The Q[o] pocket is depicted as a GRASP[64.] surface with the surrounding secondary structure elements. Helices cd1, cd2, and ef as well as parts of C, B E and F helices are shown and labeled. The heme b[L] of cyt b, 2Fe-2S cluster of the ISP, and the conserved residues that are in contact with bound inhibitors in the bc[1]-inhibitor complexes are also shown in the ball-and-stick form. Carbon atoms are colored yellow, oxygen red, nitrogen blue and sulfur green.

The above figure is reprinted by permission from Elsevier: J Mol Biol (2004, 341, 281-302) copyright 2004.