Figure 7.

Controlled disassembly of complex II from Arabidopsis by detergent treatment. The scheme shows complex II disassembly induced by incubation with 0.03% (w/v) DDM. Upon detergent treatment, the complex is split into three subcomplexes termed IIa, IIb, and IIc. The largest subcomplex (IIa; orange) consists of the matrix-exposed subunits SDH1 and SDH2. A smaller subcomplex (IIb; turquoise) represents the membrane anchor of complex II. It consists of SDH3 and SDH4 as well as the plant-specific subunits SDH6 and SDH7 (green). The smallest subcomplex (IIc; green) consists of the plant-specific and hydrophilic subunit SDH5, which forms neither part of subcomplex IIa nor IIb. The localization of the plant-specific subunit SDH8 (beige) is not known. Note that not all subunit interactions shown in the scheme have been experimentally proven. SDH7 is suggested to interact with SDH3, and SDH6 is suggested to interact with SDH4, based on evolutionary considerations (Table III). Furthermore, SDH5 occurred during evolution in parallel with SDH6 and possibly is involved in its integration into complex II. However, SDH5 also could be positioned at another location.