Site of addition of N-acetyl-galactosamine to the E1 glycoprotein of mouse hepatitis virus-A59.

Abstract

Abstract. By pulse-chase labeling with [35S]methionine and long-term labeling with 3H-sugars, the E1 glycoprotein of coronavirus MHV-A59 has been shown to acquire O-linked oligosaccharides in a two-step process. About 10 min after synthesis of the E1 protein, N-acetyl-galactosamine was added. This was followed ~10 min later by the addition of both galactose and sialic acid to give the mature oligosaccharides. This sequence of additions was confirmed by analyzing the 3H-labeled oligosaccharides bound to each of the El forms using gel filtration on P4 columns. The intracellular location of the first step was determined by exploiting the temperature sensitivity of virus release. The virus normally buds first into a smooth membrane compartment lying between the rough endoplasmic reticulum and the cis side of the Golgi stack (Tooze et al., 1984). At 31°C the virus is assembled but does not appear to enter the Golgi stacks. The addition of N-acetyl-galactosamine is unaffected although the addition of galactose and sialic acid is inhibited. These results strongly suggest that addition of N-acetyl-galactosamine occurs in this budding compartment, the morphology of which is similar to that of transitional elements and vesicles.

Intracellular transport of rubella virus structural proteins expressed from cloned cDNA

“…poorly (Baenziger & Fiete, 1979). The initial sugar of Olinked glycans is added in the ER (Pathak et al, 1988;Tooze et al, 1988). It has recently been shown that E2, but not E 1, contains O-linked glycans (Lundstr6m et al, 1991 ;; in agreement with this, we found that E2, but not E 1, bound to the O-glycan-specific lectin Jacalin (not shown).…”

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

“…Morphological (43,44,49) and biochemical (3,50,54) (44,45), consistent with the possibility that HA was in the intermediate compartment since it is unlikely that HA reached the cis-Golgi. Vesicles containing HA and p58 were not a collapsed form of the ER caused by the mutation in V.24.1 cells because the morphology of the ER was normal as assessed by staining for the ER proteins BiP and ribophorin II.…”

Oligomerization and post-translational processing of glycoprotein G of human respiratory syncytial virus: altered O-glycosylation in the presence of brefeldin A

“…The partial sensitivity of O-glycosylation to BFA, in contrast to its complete sensitivity to monensin, indicates that O-glycosylation of the G protein initiates in the trans-Golgi compartment. As noted elsewhere (Tooze et al, 1988;Collins, 1990; and references therein), the intracellular compartment(s) in which Olinked sugars are added can vary in a protein-specific and cell-specific fashion; for some proteins O-glycosylation has been reported to begin in pre-Golgi or earlyGolgi compartments whereas other proteins resemble the G protein in being O-glycosylated in more distal compartment(s) of the exocytic pathway.…”