Figure 6.

 Gic1p and Gic2p are required for polarized morphogenesis but not for MAP kinase signaling in response to pheromones. (A) Activity of the MAP kinase signaling pathway triggered by pheromones was measured by induction of the FUS1–LacZ reporter, and plotted as percent Miller Units relative to wild-type controls. (Lane 1) No α-factor added. (Lanes 2–5) α-factor added for 1 hr. The following strains were analyzed: (1 and 2) wild-type; (3) gic1Δ; (4) gic2Δ; 5: gic1Δ gic2Δ. (B) gic1Δ gic2Δ (top panel) and wild-type cells (bottom panel) are able to arrest their cell cycle in response to α-factor as assessed by halo assay. (C) gic double mutants (a and c), but not cells lacking GIC2 (b and d), are defective for polarized morphogenesis in response to α-factor. (a and b) Phase contrast photographs; (c and d) actin visualized by rhodamine-phalloidin. (D) Mating efficiencies of wild-type and gic mutant strains to a far1-c tester (Valtz and Peter 1997).