Fig. 4. Membrane proteins H36 and PM4C4 are excluded from phagocytic cups. (A) Immunofluorescence analysis of fixed cells with H36 and PM4C4 antibodies revealed a mostly surface localization of the corresponding proteins. (B) Cellular proteins were separated on acrylamide gel, transferred to a nitrocellulose membrane and detected with H36 and PM4C4 antibodies. (C-E) Cells expressing CRAC-GFP were allowed to engulf yeast particles for 10 minutes before fixation and then processed for total immunofluorescence using H36 or PM4C4 antibodies. (C) Representative pictures are shown for shallow (1) and deep (2) phagocytic cups and for newly formed (3) or early (4) phagosomes. CRAC-GFP is shown in green, the yeast particle in red and H36 staining in white. H36 staining was strongly reduced in the phagocytic cups (1,2), and in the newly formed (3) and maturing early (4) phagosomes. (D,E) Relative intensity of the H36 (D) or PM4C4 (E) staining in phagocytic cups or in phagosomes (1-4). The relative intensity of H36 and PM4C4 was determined and plotted as described in the legend to Fig. 3. Bars, 4 µm.