Figure 5.

ER SNAREs are involved in Sey1p-dependent ER fusion. (A) Sec22p is involved in Sey1p-mediated ER fusion. The indicated microsomes were incubated on ice or at 27°C in the presence of GTP or ATP/GTP for 90 min. Data represent the means ± SEM (error bars; n = 3). Lowercase letters indicate statistically different groups. A Tukey’s test between reactions was performed at 27°C. P < 0.001 between groups a–c and P < 0.01 between groups x and y. (B) Protein profiles of wild-type and sec22Δ microsomes. Yet3p was used as a loading control. (C) Affinity-purified anti-Sec22p antibodies specifically inhibit in vitro ER fusion. Gluc1 and Gluc2 microsomes were incubated on ice or at 27°C with GTP/ATP in the absence or presence of anti-Sec22p antibodies and/or his₆-Sec22p for 90 min. Data represent the means ± SEM (error bars; n = 3). Lowercase letters indicate statistically different groups (P < 0.001, Tukey’s test). (D) The function of Sec20p is required for Sey1p-dependent ER fusion. The indicated microsomes were mixed with or without anti-Sey1p antibodies and incubated on ice or at 27°C in the presence of GTP/ATP for 90 min. Lowercase letters indicate statistically different groups. Tukey’s test between reactions was performed without anti-Sey1p antibodies at 27°C (P < 0.001). (E) Protein profiles of wild-type and sec20-1 microsomes.