FIGURE 6.

Single particle EM of reconstituted supercomplex and native III₂IV₂. After reconstitution of CIII and CIV in PC/PE/CL (CL 20%) liposomes, the III₂IV₂ supercomplex was purified by sucrose gradient centrifugation after solubilization with digitonin. BN-PAGE (A) of aliquots taken from the lower half of the sucrose gradient is shown. Fractions 2 and 3 near the bottom of the sucrose gradient were enriched in III₂IV₂ supercomplex and were used for the single particle EM analysis. Projection maps of the side view of the isolated reconstituted supercomplex tetramer stained with ammonium molybdate (B) and the purified natural supercomplex stained with ammonium molybdate (C) are shown. The number of particles used for each average is indicated on the top of each projection. Scale bar, 10 nm. SC denotes supercomplex.