Localization of the Lys, Asp, Glu, Leu tetrapeptide receptor to the Golgi complex and the intermediate compartment in mammalian cells

In B the KDEL-R is labeled with 15 nm gold and the G is labeled with 10 nm gold, while in C it is KDEL-R (10 nm) and G protein (5 nm). The bulk of the KDEL-R labeling is on the cis side of the Golgi (C) stack in uninfected cells, but the distribution shifts towards the TGN after vaccinia infection. Bars, 100 nm. ysis showed that 24 % of these vesicles were labeled for the KDEL-R, whereas on average, only 4% of the COP-coated buds were labeled using two irrelevant antibodies against vaccinia,virus proteins. We conclude that a significant amount of the KDEL receptor can be detected in COP buds/vesicles after the GTP'yS treatment. Using double labeling Studies, we also found a significant labeling for rabl on these COP/bud vesicles (results not shown). The latter result is consistent with the recent data of Peter et al. (1993) and Pind et al. (1994) . In the absence of the GTP3,S, there were far fewer COP buds/vesicles, which made it much more difficult to evaluate whether significant amounts of the KDEL-R were also present in these structures under normal conditions.