Figure 3.

FITC–transferrin molecules endocytosed at 16°C do not reach the pericentriolar recycling compartment in which rab11 is concentrated. TRVb-1 cells that express the human transferrin receptor were transfected, as in Fig. 1, with the various rab11 plasmids indicated on the left of each pair of panels. The cells grown on coverslips were allowed to take up FITC–transferrin (FITC-Tf) for 1 h at 16°C, before processing, as in Fig. 1, for double immunofluorescence to localize internalized transferrin (left panels) and rab11 (right panels). The long arrows indicate the pericentriolar recycling compartment identified by the high concentration of rab11. Short arrows point to the recycling compartment in untransfected cells within the same cultures, and the arrowheads point to cytoplasmic vesicles containing both markers. Note that in all cases (left panels), FITC–transferrin is distributed in cytoplasmic vesicles and is not concentrated in the pericentriolar compartment, which in B and D is intensely labeled with anti-rab11 antibodies.