KD efficiency of XGRIM-19 and its effect on complex I activity. (A) XGRIM-19 MOs inhibit translation of XGRIM-19 mRNA in vitro. The pcDNA3-XGRIM-19 construct was transcribed and translated in vitro in the presence of XGRIM-19 MO1, MO2, or the control MO (C) at the indicated concentrations (Conc). (B) XGRIM-19 MO1 inhibits XGRIM-19 protein expression in vivo. Xenopus embryos were injected with control MO (lanes 1 and 4) or XGRIM-19 MO1 (lanes 2 and 5) at stage 1. Embryos were harvested at the indicated stages, and total lysates were prepared for Western blot analysis with anti-GRIM-19 antibody. For the rescue experiment, the hG19 mRNA was injected into two dorsal cells at stage 3 after injection with MO1 at stage 1 (lanes 3 and 6). (C) KD of GRIM-19 impairs complex I activity. The representative activities of complex I and complex II were assayed in the control (C) and XGRIM-19 KD (MO1) embryos at stage 28 by in-gel OXPHOS assay (left panel). Enzymatic activities of complex I and II in the in-gel assay were quantified by densitometry. The graph depicts the average of complex I or II activity from three independent experiments with standard deviations (right panel). **, statistical significance at a P value of <0.01, as determined by paired t test analysis.