FIGURE 2. Treatment with 0.1% Triton X-100 affects glucose-6-phosphatase activity in countin⁻ cells.

Crude microsomes were prepared from smlA⁻, Ax4 (WT), and countin⁻ cells The crude microsomes were resuspended in buffer with or without 0.1% Triton X-100, and the activities of glucose-6-phosphatase were measured as in Fig. 1. The lines show Michaelis-Menten equations fit to the data using nonlinear regression. A, glucose-6-phosphatase activities were measured in crude microsomes from smlA⁻ cells with or without Triton X-100. The presence of Triton X-100 did not significantly alter V_max and K_m. Values are the means ± S.E. from four independent assays. B, glucose-6-phosphatase activities were measured in crude microsomes from wild-type cells with or without Triton X-100. The treatment of Triton X-100 did not significantly alter the activity of the enzyme. Values are the means ± S.E. from four independent assays. C, glucose-6-phosphatase activities were measured in crude microsomes from countin⁻ cells with or without Triton X-100. The presence of Triton X-100 significantly increased the glucose-6-phosphatase activity at 0.1, 0.25, 0.5, and 0.75 mm substrate concentrations (paired t test, p < 0.05). Treatment of countin⁻ crude microsomes with Triton X-100 did not affect the K_m of glucose-6-phosphatase. Treatment of countin⁻ cells with Triton X-100 increased the V_max, but did not affect the K_m of glucose-6-phosphatase. Values are the means ± S.E. from five independent assays.