Figure 1.

(A) Schematic representation of the pheromone pathway. When α-factor binds its receptor Ste2, the GEF activity of this GPCR is activated, causing the dissociation of the heterotrimeric G protein. Free Gβγ can recruit the scaffold protein Ste5 to the membrane, initiating the MAPK cascade. Phosphorylated Fus3 and Kss1 can phosphorylate other targets that initiate the mating response. (B) Image montage of YFP-Ste5 membrane recruitment. Saturating amounts of α-factor was added at time zero (indicated by the arrow) to strain YAB3770, and changes in fluorescence distribution were followed by time-lapse confocal microscopy. BF, bright field.