Newly synthesized G protein of vesicular stomatitis virus is not transported to the Golgi complex in mitotic cells.

Abstract

Newly synthesized G protein of vesicular stomatitis virus is not transported to the surface of cultured mammalian cells during mitosis , J. Celt Biol. 97:1623-1628. To determine where intracellular transport is inhibited, we have examined the posttranslational modifications of G protein, which are indicators of specific compartments on the transport pathway. G protein in mitotic cells had only endo H-sensitive oligosaccharides containing seven or eight mannose residues, but no terminal glucose, and was not fatty acylated. These modifications were indicative of processing only by enzymes of the endoplasmic reticulum (ER). Quantitative immunocytochemistry was used as an independent method to confirm that transport of G protein out of the ER was inhibited. The density of G protein in the ER cisternae was 2.5 times greater than in infected G1 cells treated similarly. Incubation of infected mitotic cells with cycloheximide, which inhibits protein synthesis without affecting transport, did not result in a decrease in the density of G protein in the ER cisternae, demonstrating that G protein cannot be chased out of the ER. These results suggest that intracellular transport stops at or before the first vesicle-mediated step on the pathway.

Retention of secretory proteins in an intermediate compartment and disappearance of the Golgi complex in an END4 mutant of Chinese hamster ovary cells

“…Conceivably, the vesicles might require microtubules to disperse throughout the cytoplasm. This mechanism is similar to that proposed to explain the fragmentation of the Golgi during mitosis (15,26,27) and it is possible that the Golgi undergoes premature mitotic breakdown in the mutant cells. Second, the Golgi might disappear if secretory transport out of the Golgi were to continue while compensatory replacement of secreted membrane was blocked due to the lesion.…”

In vitro fusion of endocytic vesicles is inhibited by cyclin A-cdc2 kinase.

“…More likely, they may reflect a difference in pathways downstream from cyclin Acdc2 kinase in Xenopus and mammalian extracts or even differences between the way that membrane traffic is controlled during cell division in the two systems. Several such differences are apparent in vivo; endoplasmic reticulum-Golgi transport is blocked in mammalian cells (Featherstone et al, 1985) but not in maturing Xenopus oocytes (Ceriotti and Colman, 1989;Kanki and Newport, 1991), whereas the inverse is found for transGolgi-cell surface transport (Kreiner and Moore, 1990;Leaf et al, 1990). It is not known whether the endocytic pathway is blocked in maturing oocytes.…”

Golgi Ribbon Unlinking: An Organelle-Based G2/M Checkpoint

“…22,25 This effect is likely due to the cessation of ER-Golgi and intra-Golgi transport that is observed in metaphase leading partly to an accumulation of COPI vesicles. [35][36][37] Several CDK1-phosphorylated substrates functioning in the early secretory pathway, such as Rab1, 38 GM130, [39][40] GRASP65 [41][42][43] and p47, 44 could contribute to this.…”