Figure 4. T cell receptor (TCR) stimulation triggers loading of FM1-43 into the ER, NE and Golgi

Subcellular distribution of FM1-43 revealed by photoconversion reaction product (PCRP, black staining) before (A) and (B) after TCR stimulation. (i) and (ii) are enlargements of corresponding boxed areas in (A) and (B). (A) A cell after 20 min of incubation with FM1- 43 alone (Control). PCRP is present within primary endocytic compartments (tubular-vesicular structures) and multi-vesicular bodies (MVB). ER (arrowheads), NE (arrows), and Golgi (G) do not contain FM1-43. (B, C) PCRP is present within ER, NE and Golgi in cells incubated for 20 min with FM1-43+PHA, a TCR agonist. N â€" nucleus. Bars, 2 mm in (A) and (B) and 500 nm in (i) and (ii).