S. cerevisiae (Mata his3-Δ200 leu2-3, 112 ura3-52 bar1Δ::LEU2 ABP140-3GFP::HIS3) were grown to an OD600 of 0.2 in 1.25 ml of YPD, briefly centrifuged, and resuspended in 50 μl of synthetic media (SM) with 1% (wt/vol) BSA and 5 μM Alexa-α-factor. After incubation on ice for 2 h, cells were washed into ice-cold SM containing 1% BSA. Internalization was initiated by the addition of ice-cold SM containing 4% Glucose and amino acids and then transferring cells to a glass slide at room temperature. Simultaneous imaging of red and green fluorescence was performed by using an Olympus IX81 microscope equipped with a ×100/NA 1.45 (Olympus) objective, Orca-ER cooled CCD camera (Hamamatsu), and an image splitter (Dual-View; Optical Insights) that divided the red and green components of the images with a 565-nm dichroic mirror and passed the red component through a 630/50-nm filter and the green component through a 530/30-nm filter.