Cytometry analysis of COS1(B3GALNT1) cells transfected with M_GBGT1, H-ABO-A, and 8 representative human A transferase derivative constructs. Cells were cotransfected with DNA from selected expression constructs together with a vector expressing mRFP. Cells were then detached and stained with anti-FORS1 antibody followed by AF488-conjugated secondary antibody. The first 2 panels correspond to M_GBGT1 transfection. On the left, the selection of single viable cell population by forward (FSC-A) and side (SSC-A) scattering amplitudes is depicted. Events are plotted in pseudocolor, with red representing higher frequency and dark blue the lowest. This selection was maintained for all the other samples. The right panel shows a contour plot of the mRFP fluorescence intensity, used as transfection control, on the y-axis, and the fluorescence corresponding to FORS1 on the x-axis. Both axes are on logarithmic scales. The upper red rectangle represents mRFP-positive cells, and the percentage of mRFP-positive cells is also indicated at the upper left corner. The rightmost green rectangle corresponds to AF488 fluorescence, and the percentage of FORS1-positive cells is indicated at the lower right corner. The other panels show the graph for the other constructs, using the same gate, second row: H_ABO-A, H_ABO-A(Met69Thr), and H_ABO-A(Met69Ser); third row: H-ABO-A(GlyGlyAla), H_ABO-A(Met69Thr&GlyGlyAla), and H_ABO-A(Met69Thr&MetGlyAla); and fourth row: H_ABO-A(delEx4), H_ABO-A(delEx4&GlyGlyAla), and H_ABO-A(delEx3&GlyGlyAla).