The rate of uptake of ThDP by mitochondria isolated from normal and TRMA lymphoblasts. Mitochondria were isolated from normal (open squares) or TRMA (open circles) lymphoblasts and were incubated for 15 minutes with various concentrations of radioactive ThDP. Mitochondrial-associated counts were determined, and the velocity (V) (pmol ThDP per mg mitochondrial protein per min.) is plotted versus the concentration in micromolar of ThDP ([S]). The inset shows the Lineweaver-Burk plot (1/V vs. 1/S) of the high affinity component of ThDP uptake for normal (open squares) and TRMA (open circles) derived mitochondria.