Figure 1.

Identification of Erv proteins. COPII-coated vesicles were synthesized in vitro from ER membranes in the presence of COPII proteins (+), were solubilized in sample buffer, and were resolved on a 15% polyacrylamide gel. As a negative control, a mock reaction without COPII proteins (−) was performed. Proteins were silver stained for this figure. For mass spectroscopy, proteins were stained with colloidal blue, and individual bands were excised.