Figure 4.

Pab1p association with COPI-coated vesicles is dependent on mRNA. COPI vesicles were generated from Golgi membranes in the presence of GTP-γ-S and COPI components. In one experiment, RNase (200 μg) was added to the budding reaction. The vesicles were purified over a velocity gradient and subsequently floated on a Nycodenz gradient. Fractions were collected from the top, separated by SDS-PAGE, and analyzed by immunoblot. The arrows indicate the direction of movement of lipid particles within the gradient. Nonmembrane-associated proteins remain in the load at the bottom of the gradient. The vesicles peak in fractions 5 and 6.