Figure 8.

Modulation of substrate compartmentalization by changes in cellular metabolism. Four different cell types transfected with the indicated constructs as in Figure 7A were plated into four separate sets of 96-well plates. The plates were analyzed for luciferase activity on four successive days, beginning on the day of replating (after being allowed 6 h to recover). The results for each cell type are on separate graphs. In each instance, the measurements from any one day were normalized to the activity observed for Prl₁₀-TF in that cell type, which was arbitrarily set to 100. The normalized activities for each of the 4 d are shown in bars of increasing darkness of gray (darkest bar is day 4). Thus, by definition, Prl₁₀-TF values do not vary on these graphs from day to day. Relative to this arbitrary standard, changes for the other constructs can be observed in some, but not all instances in a cell-type and substrate-specific manner. In this experiment, cells began at ∼50% density (i.e., actively growing and dividing) and became confluent between the second and third set of measurements.