Fig 1.

Ablation of RISP leads to CIII deficiency. (A) Diagram shows the floxed allele containing 3 loxP sites (triangles) flanking exon 2 of the UQCRFS1 gene (encoding RISP) and a selection cassette (TK/Neo) present in the knock-in mouse, the deletion allele obtained after Cre recombination, and the wild-type allele. (B) Efficiency of recombination of the floxed gene. Knockout clones only showed the band corresponding to the deletion allele by multiplex PCR (primers shown in panel A by arrows), indicating complete recombination. The wild-type (WT) allele was amplified from skin fibroblasts from a wild-type mouse. (C) Enzymatic activities of CIII, CIV, and citrate synthase (CS) determined spectrophotometrically. Values represent the means and standard deviations of specific activities. Statistical significance is shown by an asterisk (P ≤ 0.05). (D) Western blot of mitochondrial proteins and OXPHOS complex subunits (CI, NDUFA9; CIII, Core1, Core2, and RISP; and CIV, Cox1). VDAC1 and Tim23 were used as mitochondrial loading controls.