FIGURE 4.

hCOA3 knockdown induces a rapid degradation of the newly synthesized COX1. A, quantitative RT-PCR of mitochondrial mRNAs (left panel) and hCOA3 mRNA (right panel) in untransfected HeLa cells (untransfected), HeLa cells transfected with non-interfering siRNAs (Ki #2) or siRNAs against hCOA3 (siRNAs hCOA3) 96 h after transfection. Data represent mean values ± S.D. ***, p < 0.001 (n = 5). B, newly synthesized mitochondrial polypeptides were labeled with [³⁵S]methionine for 30 min. Mitochondrial translation products were detected through direct autoradiography of the gels. C, newly synthesized mitochondrial polypeptides were labeled with [³⁵S]methionine for 30 min. Cells were then washed and incubated in regular DMEM for 2, 4, or 7 h. Mitochondrial translation products were detected through direct autoradiography of the gels. D, quantification of COX1 labeling in pulse experiments. Data represent mean values ± S.D. **, p < 0.01 (n = 4). E, quantification of COX1 labeling in pulse-chase experiments. Data represent mean values ± S.D. *, p < 0.05; **, p < 0.01 (n = 4).