Figure 1. COPII vesicles lose their ability to bind TRAPPI after Uso1p acts.
a, Vesicles formed in vitro with cytosol +/− Golgi were incubated with TRAPPI-containing beads and the precipitated radiolabeled cargo was counted. Cytosol and Golgi were isolated from either wild type or the bet3-1 mutant. Error bars represent S.D., N=6. In a–d, the percent transport observed for the total reaction is reported above the bar graphs. For b, and d, cytosol and Golgi fractions, derived from wild type, were formed with: anti-Ypt1p (12 μg), anti-Sec22p (12 μg), anti-Sly1p (20 μg) antibodies, or IgG (12 μg or 20 μg, respectively). Error bars represent S.D., N=4. c, Vesicles were formed with uso1-1 fractions at 27°C or 17°C and incubated with TRAPPI-containing beads. N=2, bars show the range. (**P<0.01, ****P<0.0001 Student’s t test).