Fig. 3.

Continuous PtdIns(4,5)P₂ synthesis is required for stable accumulation of Ste5 at the shmoo tip during pheromone response. (A–E) Exponentially growing cultures of ste5Δ cells (A), ste5Δ mss4^ts cells (B), ste5Δ stt4^ts cells (C), ste5Δ pik1^ts cells (D), or ste5Δ stt4^ts pik1^ts cells (E), each harboring a low-copy (CEN) vector expressing from the STE5 promoter Ste5-(GFP)₃, were treated with 20 μM α-factor for 30 min, at which point half of each culture was left at the permissive temperature (26 °C) and half was shifted to the restrictive temperature (37 °C). After 90 min, cells in each culture were examined by standard epifluorescence microscopy. Each panel depicts a collage of representative cells at each time point: arrowheads, mating projections where Ste5-(GFP)₃ accumulated; arrows, mating projections lacking Ste5-(GFP)₃.