Fig. 5.

Alterations of the respiratory chain and oxidative phosphorylation complex assembly as assessed by blue native gel electrophoresis. Protein complexes derived from identical amounts of enriched mitochondria from 4- and 16-month-old wild-type (WT), heterozygous (HET), and homozygous (HOM) R349P desmin knock-in littermates were separated by blue native electrophoresis in 3–16 % acrylamide gradient gels. a, b Gels were Coomassie stained or used for immunoblotting against complex I subunits or “OXPHOS multiplex” using an antibody mix against all respiratory chain and oxidative phosphorylation complexes. Note the reduced amounts of complex I as free component and as part of the large supercomplex S _L in young and aged homozygous mice (asterisks), and as part of supercomplex S _L in aged heterozygous mice (arrowheads). c A native gel as in panel (a) was used for complex I activity visualization, which demonstrated a corresponding reduction of the enzymatic activity. Mitochondrial complexes are indicated: I, complex I; II, complex II; III, dimeric complex III; IV, complex IV; V, complex V; S _0-1, respiratory supercomplexes containing complex I, dimeric complex III and 0 to 1 copy of complex IV; S _L, larger supercomplex containing two complex I and one complex III dimer