Localization of glycosylation sites in the golgi apparatus using immunolabeling and cytochemistry

Roth, Jürgen

doi:10.1002/jemt.1060170202

Cited by 40 publications

(23 citation statements)

References 87 publications

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“…Moreover, individual enzyme molecules would be expected to visit different cisternae in the stack. Both of these predictions fit the experimental data [17][18][19][25][26][27]. Our model makes two additional predictions.…”

Section: Discussionsupporting

confidence: 78%

A cisternal maturation mechanism can explain the asymmetry of the Golgi stack

1997

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Morphological data suggest that Golgi cisternae form at the cis-face of the stack and then progressively mature into trans-cisternae. However, other studies indicate that COPI vesicles transport material between Golgi cisternae. These two observations can be reconciled by assuming that cisternae carry secretory cargo through the stack in the anterograde direction, while COPI vesicles transport Golgi enzymes in the retrograde direction. This model provides a mechanism for cisternal maturation, if Golgi enzymes compete with one another for packaging into COPI vesicles, we can account for the asymmetric distribution of enzymes across the stack.

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Section: Discussionsupporting

confidence: 78%

A cisternal maturation mechanism can explain the asymmetry of the Golgi stack

1997

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“…Subsequently, Golgi-localized glycosyltransferases mediate the transfer of sugar residues from nucleotide sugar donors onto the N-glycans. In mammalian cells, it has been shown that glycosidases and glycosyltransferases are distributed along the Golgi from the cisto the trans-regions in the order in which they process N-glycans; however, there is some overlap and variation in their distribution depending on the cell type (Roth, 1991;Nilsson et al, 1993a;Velasco et al, 1993;Rabouille et al, 1995;Idgoura et al, 1999). With the exception of a-glucosidase II (Trombetta et al, 1996(Trombetta et al, , 2001; P. Soussilane, C. Saint-Jore-Dupas, and V. Gomord, unpublished data), which is a soluble heterodimer, glycosidases and glycosyltransferases responsible for the N-glycan maturation are type II membrane proteins with a short N-terminal cytoplasmic tail (CT), a single transmembrane domain (TMD), a stem region (S), and a large catalytic domain associated with the enzyme activity.…”

Section: Introductionmentioning

confidence: 99%

PlantN-Glycan Processing Enzymes Employ Different Targeting Mechanisms for Their Spatial Arrangement along the Secretory Pathway

et al. 2006

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The processing of N-linked oligosaccharides in the secretory pathway requires the sequential action of a number of glycosidases and glycosyltransferases. We studied the spatial distribution of several type II membrane-bound enzymes from Glycine max, Arabidopsis thaliana, and Nicotiana tabacum. Glucosidase I (GCSI) localized to the endoplasmic reticulum (ER), a-1,2 mannosidase I (ManI) and N-acetylglucosaminyltransferase I (GNTI) both targeted to the ER and Golgi, and b-1,2 xylosyltransferase localized exclusively to Golgi stacks, corresponding to the order of expected function. ManI deletion constructs revealed that the ManI transmembrane domain (TMD) contains all necessary targeting information. Likewise, GNTI truncations showed that this could apply to other type II enzymes. A green fluorescent protein chimera with ManI TMD, lengthened by duplicating its last seven amino acids, localized exclusively to the Golgi and colocalized with a transGolgi marker (ST52-mRFP), suggesting roles for protein-lipid interactions in ManI targeting. However, the TMD lengths of other plant glycosylation enzymes indicate that this mechanism cannot apply to all enzymes in the pathway. In fact, removal of the first 11 amino acids of the GCSI cytoplasmic tail resulted in relocalization from the ER to the Golgi, suggesting a targeting mechanism relying on protein-protein interactions. We conclude that the localization of N-glycan processing enzymes corresponds to an assembly line in the early secretory pathway and depends on both TMD length and signals in the cytoplasmic tail.

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“…The N-glycan maturation machinery is relatively well known in mammals and about one hundred mammalian Golgi glycosyltransferases have been cloned and sequenced. While there is little amino acid sequence similarity between many of Nglycan maturation enzymes, they were shown to share a common type II membrane protein structure with a short Nterminal cytosolic tail, a single 17 to 22 amino acid transmembrane domain (TMD), a relatively short lumenal stem region and a large lumenal catalytic domain (for a review see Kleene and Berger, 1993;Breton et al, 2001).The distribution of these glycosyltransferases in the Golgi was also extensively studied (Roth, 1991;Rabouille et al, 1995;Allende et al, 2000;Zerfaoui et al, 2002). Although recent The Plant Journal (2003) 33, 189-203 ß 2003 Blackwell Publishing Ltd evidences suggest some overlap in the distribution of mammalian glycosyltransferases between Golgi subcompartments, several signals and mechanisms responsible for their localization in the Golgi have been identified.…”

Section: Introductionmentioning

confidence: 99%

Structural requirements for Arabidopsisβ1,2‐xylosyltransferase activity and targeting to the Golgi

Pagny¹,

Bouissonnie²,

Sarkar³

et al. 2003

The Plant Journal

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SummaryCharacterization of a b1,2-xylosyltransferase from Arabidopsis thaliana (AtXylT) was carried out by expression in Sf9 insect cells using a baculovirus vector system. Serial deletions at both the N-and C-terminal ends proved that integrity of a large domain located between amino acid 31 and the C-terminal lumenal region is required for AtXylT activity expression. The influence of N-glycosylation on AtXylT activity has been evaluated using either tunicamycin or mutagenesis of potential N-glycosylation sites. AtXylT is glycosylated on two of its three potential N-glycosylation sites (Asn51, Asn301, Asn478) and the occupancy of at least one of these two sites (Asn51 and Asn301) is necessary for AtXylT stability and activity. Contribution of the N-terminal part of AtXylT in targeting and intracellular distribution of this protein was studied by expression of variably truncated, GFP-tagged AtXylT forms in tobacco cells using confocal and electron microscopy. These studies have shown that the transmembrane domain of AtXylT and its short flanking amino acid sequences are sufficient to specifically localize a reporter protein to the medial Golgi cisternae in tobacco cells. This study is the first detailed characterization of a plant glycosyltransferase at the molecular level.

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Localization of glycosylation sites in the golgi apparatus using immunolabeling and cytochemistry

Cited by 40 publications

References 87 publications

A cisternal maturation mechanism can explain the asymmetry of the Golgi stack

A cisternal maturation mechanism can explain the asymmetry of the Golgi stack

PlantN-Glycan Processing Enzymes Employ Different Targeting Mechanisms for Their Spatial Arrangement along the Secretory Pathway

Structural requirements for Arabidopsisβ1,2‐xylosyltransferase activity and targeting to the Golgi

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