Complex III of Electron Transport Chain: Difference between revisions

Complex III of the electron transport chain contains as many as 11 subunits per monomer.  The structure shown to the right has 9. (The 'initial scene' green link available in the Jmol applet shows the dimer structure along with Heavy Chain (Vh) Of Fv-Fragment, Light Chain (Vl) Of Fv-Fragment and Cytochrome C, Iso-1 all of which are a part of 1KYO.PDB.) <scene name='Complex_III_of_Electron_Transport_Chain/Labels_applied/1'>Show orientation</scene> of the complex within the inner mitochondrial membrane with labels. <scene name='Complex_III_of_Electron_Transport_Chain/View_one_subunit/1'>Coloring one subunit grey</scene> reveals that one of the peptides of each subunit invades the space of the other subunit. <scene name='Complex_III_of_Electron_Transport_Chain/View_3_active_subunits/1'>Three of the subunits</scene> of each monomeric unit have a direct role in the passage of electrons in the respiratory chain. The subunits that are colored are active in the electron transport chain. The peptides have other catalytic activities and functions, and the interior spaces which are created by the positions of the other subunits have a role in the movement of the substrates from one active site to another active site within the complex. The two subunits of cytochrome b (colored green) for the most part are buried in the complex and have minimal exposure to the intermembrane space.  Cytochrome c1 subunits are positioned on top of cytochrome b and their outer surfaces are exposed to the intermembranal space.  They are held in place by helical tails that extends deep into the complex. The Rieske subunits are Fe/S proteins with three domains: membrane domain (long helical segment that extends into the complex), head domain which contains the Fe/S center and hinge domain (short segment between the other two).