Figure 10.

Syntaxin 8 functions in an early step of protein transport from EEs to LEs. Tf and EGF trafficking was measured using an SLO-permeabilized HeLa cell assay as described in MATERIALS AND METHODS. EGF (A) or Tf (B)-loaded and SLO-permeabilized cells were incubated without (C−) or with (remaining samples) cytosol for 2 h at 37°C with 100 μg/ml anti-syntaxin 6 (anti-Syn6), anti-syntaxin 8 (anti-Syn8), anti-syntaxin 7 (anti-Syn7), or rabbit IgG (IgG). The data shown are the means of at least three independent experiments ± SEM An asterisk marks the statistically significant difference at p < 0.05. (C) SLO-permeabilized HeLa cells were preincubated with varying concentrations of anti-syntaxin 8 antibody before measuring the EGF degradation. Data are expressed as a percentage of total cytosol-dependent EGF degradation. (D) EGF-loaded HeLa cells were chased for varying amounts of time at 37°C followed by SLO permeabilization. Cells were then preincubated with 100 μg/ml anti-syntaxin 8 antibody and EGF degradation measured as described above. These data are expressed as a percentage of total cytosol-dependent EGF degradation.