Characterization of the budding compartment of mouse hepatitis virus: evidence that transport from the RER to the Golgi complex requires only one vesicular transport step

In the present study, we could show that the compartment where MHV buds, as well as the whole Golgi region, was highly enriched in/3-cop-containing vesicles after treatment with GTP~/S in permeabilized cells. A similar effect was seen in rat liver Golgi preparations and other tissue culture cells where a large accumulation of ~-cop containing vesicles was observed after GTP3,S treatment (Melangon et al., 1987; Duden et al., 1991a; Orci et al., 1993; Wilson et al., 1993) . In the absence of GTP'yS the labeling with/3-cop was too low to allow any firm conclusions. We assume that GTP~S treatment simply locks/%cop to budding vesicles without changing its localization. In this study GTP-yS had no qualitative effect on the localization of p58 nor any quantitative effect on the distribution of PDI.