Influence of N-Glycosylation and N-Glycan Trimming on the Activity and Intracellular Traffic of GD3 Synthase

Martina, José A.; Daniotti, José L.; Maccioni, Hugo J. F.

doi:10.1074/jbc.273.6.3725

Cited by 77 publications

(80 citation statements)

References 34 publications

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“…In previous works, we demonstrated in CHO-K1 cells that most of the Golgi-located chick Sial-T2 was in an Endo-H-sensitive NANase-insensitive form. However, a minor secreted form lacking about 40 amino acids from the N terminus was Endo-H-resistant and NANase-sensitive, indicating that the cells were able to process N-glycans to an Endo-H-resistant form (23,34). Bearing in mind these antecedents and by analyzing the N-glycan status, we decided to explore whether the plasma membrane-associated Sial-T2 partially or totally contributes to the soluble extracellular fraction of the enzyme.…”

Section: Expression Of Sial-t2 At the Cell Surface Does Not Depend Onmentioning

confidence: 99%

Neobiosynthesis of Glycosphingolipids by Plasma Membrane-associated Glycosyltransferases*

Crespo¹,

Demichelis²,

Daniotti

2010

Journal of Biological Chemistry

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Gangliosides, complex glycosphingolipids containing sialic acids, are synthesized in the endoplasmic reticulum and in the Golgi complex. These neobiosynthesized gangliosides move via vesicular transport to the plasma membrane, becoming components of the external leaflet. Gangliosides can undergo endocytosis followed by recycling to the cell surface or sorting to the Golgi complex or lysosomes for remodeling and catabolism. Recently, glycosphingolipid catabolic enzymes (glycohydrolases) have been found to be associated with the plasma membrane, where they display activity on the membrane components. In this work, we demonstrated that ecto-ganglioside glycosyltransferases may catalyze ganglioside synthesis outside the Golgi compartment, particularly at the cell surface. Specifically, we report the first direct evidence of expression and activity of CMP-NeuAc: GM3 sialyltransferase (Sial-T2) at the cell surface of epithelial and melanoma cells, with membrane-integrated ectoSial-T2 being able to sialylate endogenously synthesized GM3 ganglioside as well as exogenously incorporated substrate. Interestingly, we also showed that ecto-Sial-T2 was able to synthesize GD3 ganglioside at the cell surface using the endogenously synthesized cytidine monophospho-N-acetylneuraminic acid (CMP-NeuAc) available at the extracellular milieu. In addition, the expression of UDP-GalNAc:LacCer/GM3/ GD3 N-acetylgalactosaminyltransferase (GalNAc-T) was also detected at the cell surface of epithelial cells, whose catalytic activity was only observed after feeding the cells with exogenous GM3 substrate. Thus, the relative interplay between the plasma membrane-associated glycosyltransferase and glycohydrolase activities, even when acting on a common substrate, emerges as a potential level of regulation of the local glycosphingolipid composition in response to different external and internal stimuli.

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Section: Expression Of Sial-t2 At the Cell Surface Does Not Depend Onmentioning

confidence: 99%

Neobiosynthesis of Glycosphingolipids by Plasma Membrane-associated Glycosyltransferases*

Crespo¹,

Demichelis²,

Daniotti

2010

Journal of Biological Chemistry

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“…plex with a functional ScSTT3 subunit can transfer even partially assembled core oligosaccharide to proteins, whereas upon depletion of functional STT3, OST activity decreases significantly and only fully assembled core oligosaccharide is a functional OST substrate, albeit with very low efficiency (Zuffery et al, 1995). Several proteins require N-glycosylation to express their normal function, including meprin A metalloproteinase (Kadowaki et al, 2000), GD3 synthase (CMP-NeuAc:GM3 ␣-2,8-sialyltransferase) (Martina et al, 1998), GM2 synthase (UDP-GalNAc:GM3 ␤-1,4-N-acetylgalactosaminyltransferase) (Haraguchi et al, 1995), and high-affinity immunoglobulin E receptor (Letourneur et al, 1995).…”

Section: Stt3 Genes Have Isoform-specific Functionsmentioning

confidence: 99%

The STT3a Subunit Isoform of the Arabidopsis Oligosaccharyltransferase Controls Adaptive Responses to Salt/Osmotic Stress

Koiwa¹

2003

THE PLANT CELL ONLINE

191

287

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Arabidopsis stt3a-1 and stt3a-2 mutations cause NaCl/osmotic sensitivity that is characterized by reduced cell division in the root meristem. Sequence comparison of the STT3a gene identified a yeast ortholog, STT3 , which encodes an essential subunit of the oligosaccharyltransferase complex that is involved in protein N -glycosylation. NaCl induces the unfolded protein response in the endoplasmic reticulum (ER) and cell cycle arrest in root tip cells of stt3a seedlings, as determined by expression profiling of ER stress-responsive chaperone ( BiP -GUS ) and cell division ( CycB1;1 -GUS ) genes, respectively. Together, these results indicate that plant salt stress adaptation involves ER stress signal regulation of cell cycle progression. Interestingly, a mutation ( stt3b-1 ) in another Arabidopsis STT3 isogene ( STT3b ) does not cause NaCl sensitivity. However, the stt3a-1 stt3b-1 double mutation is gametophytic lethal. Apparently, STT3a and STT3b have overlapping and essential functions in plant growth and developmental processes, but the pivotal and specific protein glycosylation that is a necessary for recovery from the unfolded protein response and for cell cycle progression during salt/osmotic stress recovery is associated uniquely with the function of the STT3a isoform.

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“…Thus, movement of gp65-p22 phox into the Golgi complex required at least 4 h. A role for the extensive glycosylation of gp91 phox has not been reported, although N-glycans have been shown to serve as sorting signals in the trans-Golgi network (64). Moreover, glycosylation can play a role in protein folding and stability, as observed with GD3 synthase or human thyroperoxidase (65,66). However, we observed that glycosylation was not required for the formation of the flavocytochrome b heterodimer since the binding of p22 phox with unglycosylated gp65 was unaffected (Fig.…”

Section: Glycosylation and Heterodimer Formation-because The Binding mentioning

confidence: 99%

Processing and Maturation of Flavocytochromeb 558 Include Incorporation of Heme as a Prerequisite for Heterodimer Assembly

DeLeo¹,

Burritt²,

Yu³

et al. 2000

Journal of Biological Chemistry

152

149

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The phagocyte NADPH-dependent oxidase generates superoxide by reducing molecular oxygen through a transmembrane heterodimer known as flavocytochrome b 558 (flavocytochrome b). We investigated the biosynthesis of flavocytochrome b subunits gp91 phox and p22 phox to elucidate features of flavocytochrome b processing in myeloid cells. Although the gp91 phox precursor, gp65, was processed to gp91phox within 4 -8 h of chase, unassembled gp65 and p22 phox monomers were degraded by the cytosolic proteasome. gp65 associated with p22 phox post-translationally, within 1-4 h of chase, but prior to its modification in the Golgi complex. Moreover, p22 phox coprecipitated with unglycosylated gp91 phox primary translation product made in the presence of tunicamycin, suggesting that heterodimer formation does not require glycosylation. Blocking heme synthesis with succinyl acetone completely inhibited heterodimer formation, although biogenesis of gp65 and p22 phox was unaffected. In succinyl acetone-treated cells, p22 phox and gp65 were degraded completely by 8 h of chase, a process mediated by the cytosolic proteasome. Taken together, these data suggest that the formation of the gp65-p22 phox heterodimer is relatively inefficient and that acquisition of heme by gp65 precedes and is required for its association with p22 phox , a process that requires neither the addition of N-linked oligosaccharides nor modification in the Golgi complex.

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Influence of N-Glycosylation and N-Glycan Trimming on the Activity and Intracellular Traffic of GD3 Synthase

Cited by 77 publications

References 34 publications

Neobiosynthesis of Glycosphingolipids by Plasma Membrane-associated Glycosyltransferases*

Neobiosynthesis of Glycosphingolipids by Plasma Membrane-associated Glycosyltransferases*

The STT3a Subunit Isoform of the Arabidopsis Oligosaccharyltransferase Controls Adaptive Responses to Salt/Osmotic Stress

Processing and Maturation of Flavocytochromeb 558 Include Incorporation of Heme as a Prerequisite for Heterodimer Assembly

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