Figure 3.

pik1^ts cells show defects in both PtdIns(4)P and PtdIns(4,5)P₂ synthesis. Wild-type (SEY6210), pik1^ts (AAY104), and stt4^ts/pik1^ts double mutant (AAY105) cells were grown to mid log phase, shifted to the appropriate temperature for 10 min, labeled with myo-[2-³H]inositol for 10 min, and chased in the presence of excess unlabeled myo-inositol for 30 min. Cellular lipids were recovered, deacylated, and separated by HPLC as described in Figure 1. Levels of deacylated products corresponding to the indicated phosphoinositides are shown. (A) A comparison of phosphoinositide levels in wild-type and pik1^ts cells at 26 and 38°C. (B) A comparison of phosphoinositide levels in wild-type and stt4^ts/pik1^ts double mutant cells at 26 and 38°C. These data represent means ± ranges of at least three independent experiments.