Localization of rTSβ and rTSγ to mitochondria. A. Presence of rTSβ in both cytosol and organelle fractions. Five μg of protein from the organelle (lane 1), cytosol (lane 2), or 5 μg each of the organelle plus cytosol (lane 3) were resolved by gel electrophoresis, blotted and probed for the presence of the indicated proteins. B. Gradient fractionation of mitochondria and lysosomes. The crude organellar suspension from CCRF-CEM cells was fractionated on a linear iodixanol gradient as described. Individual fractions were collected and assayed for GDH activity and protein content. —, Density (g/ml) of fractions from a mock 5–20% iodixanol gradient; -◊-, GDH activity; -○-, Protein content. C. Western blot. Five μl of each fraction was denatured and processed for Western blotting as described.