Supplemental Material

This article contains the following supporting material:

• Supplemental Figure 1 - Yor1p uptake into COPII vesicles is dependent on the B-site of Sec24p. Wild-type cells expressing HA-tagged Yor1p were radiolabelled for 10 min, permeabilized and used in in vitro vesicle budding reactions. Membranes were treated with urea prior to budding to remove endogenous wild-type COPII proteins (Miller et al., 2003). Budding reactions contained Sar1p•GTP and Sec13/31p and either lacked Sec23/24p (left lanes) or were supplemented with wild-type or mutant Sec23/24p as indicated (middle and right lanes). Vesicles (+) were separated from total membranes (T) and subjected to immunoprecipitation using anti-HA antibodies. The percentage of Yor1p released into the vesicle fraction was quantified by PhosphorImage analysis and is indicated below each lane.