FIGURE 1.

Mitochondrial preparations from human hepatocytes and cell lines. HepG2 cells were cultured, harvested, homogenized, and mitochondrially enriched fractions prepared as described under “Experimental Procedures.” Mitochondria-enriched pellets (75 μg of protein) were visualized by transmission electron microscopy (panel 1 = 13,500×; panels 2 and 3 = 92,000× (A)), and total cell and mitochondrial extracts from human liver biopsies were subjected to Western immunoblotting analysis for ALAS-1 protein expression (B). VDAC1/porin, calnexin, and GAPDH expression served as mitochondrial, endoplasmic reticulum/microsome, and total lysate controls, respectively.