Cdc42p and Fus2p colocalize specifically at the ZCF. (A) Cdc42p and Fus2p colocalize at the ZCF and at the remnant cell walls. GFP–CDC42 fus2Δ cells containing Fus2p–mCherry₁₀₄ on a plasmid (pMR5821) were mated to a fus1Δfus2Δ strain (JY429) for 2.5 h at 30°, fixed with 2% formaldehyde, and imaged. (B) Cdc42p and Fus2p do not colocalize in shmoos. The same MATa strain as in A was imaged after incubation with pheromone for 1.5 h. (C) Quantification of the distance between GFP and mCherry fluorescence peaks for both prezygotes and shmoos. n = 50 prezygotes or shmoos imaged. Error bars denote the SEM. Data in C were pooled from three independent experiments. Bars, 2 µm.