Average distribution of four gradient-sensing proteins on the PM of mating cells orienting toward a partner. MAT a cells expressing Ste2 (the receptor), Gβ, Far1, and Sst2 tagged with GFP in situ were mixed with an equal number of MATα cells and imaged from cytokinesis to fusion. Identical imaging parameters were used for all reporters. (A) Illustration of the method used to normalize and average the signal distributions exhibited by multiple cells. The PM signals of cells that formed zygotes were quantified with ImageJ. 20 cells expressing each reporter were normalized by the DS-to-CS distance, and the average signal distributions were generated as described in Materials and methods. (B) The plots show the average distribution ± SEM (light green shadow) for each reporter just before initiation of redistribution from the DS (Start), after one-third and two-thirds of the time it took to complete redistribution, and having just stabilized at the CS (Finish). The dashed blue and red lines mark the DS and CS, respectively; the red arrowheads indicate the leading peaks during redistribution. F.I., fluorescence intensity.