Distribution of glycosyltransferases among Golgi apparatus subfractions from liver and hepatomas of the rat

Hartel‐Schenk, Sabine; Minnifield, N; Reutter, Werner; Hanski, C.; Bauer, Christian; Morré, D. James

doi:10.1016/0304-4165(91)90019-d

Cited by 35 publications

(17 citation statements)

References 41 publications

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“…We now examine possible mechanisms to explain the exclusion of Gal␣(1,3)Gal synthesis by HT. Our strategy was based on the observations that HT is located in the medial Golgi (16) and that GT is located in the trans-Golgi (17). Thus, as proteins pass through the Golgi network, they are likely to encounter HT before GT.…”

Section: Discussionmentioning

confidence: 99%

Switching Amino-terminal Cytoplasmic Domains of α(1,2)Fucosyltransferase and α(1,3)Galactosyltransferase Alters the Expression of H Substance and Galα(1,3)Gal

Osman

McKenzie

Mouhtouris

et al. 1996

Journal of Biological Chemistry

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When ␣(1,2)fucosyltransferase cDNA is expressed in cells that normally express large amounts of the terminal carbohydrate Gal␣(1,3)Gal, and therefore the ␣(1,3)galactosyltransferase (GT), the Gal␣(1,3)Gal almost disappears, indicating that the presence of the ␣(1,2)fucosyltransferase (HT) gene/enzyme alters the synthesis of Gal␣(1,3)Gal. A possible mechanism to account for these findings is enzyme location within the Golgi apparatus. We examined the effect of Golgi localization by exchanging the cytoplasmic tails of HT and GT; if Golgi targeting signals are contained within the cytoplasmic tail sequences of these enzymes then a "tail switch" would permit GT first access to the substrate and thereby reverse the observed dominance of HT. Two chimeric glycosyltransferase proteins were constructed and compared with the normal glycosyltransferases after transfection into COS cells. The chimeric enzymes showed K m values and cell surface carbohydrate expression comparable with normal glycosyltransferases. Coexpression of the two chimeric glycosyltransferases resulted in cell surface expression of Gal␣(1,3)Gal, and virtually no HT product was expressed. Thus the cytoplasmic tail of HT determines the temporal order of action, and therefore dominance, of these two enzymes.Glycosylation is a complex form of posttranslational modification of proteins where glycosyltransferases, located in the endoplasmic reticulum and Golgi apparatus, catalyze the sequential transfer of monosaccharides from nucleotide sugars to saccharide acceptors resulting in mature oligosaccharides (1). Thus the large number of both N-and O-linked carbohydrate side chains, consisting of structures of three or 4 simple monosaccharides, can have the different glycosylation patterns generated by the sequential and coordinated action of more than 100 different glycosyltransferases (2). In this process, the product of one transferase serves as the substrate for the next transferase (3), with the differences in the glycosylation pattern being due to variation in the topology and function and the level of expression of the glycosyltransferase within the Golgi complex (3).Evidence to date based on immunoelectron microscopy and cell fractionation studies suggests that the glycosyltransferases are sequentially distributed within the Golgi compartments in approximately the observed order of glycosylation (4). A number of studies using hybrid molecules have examined mechanisms for the sorting and retention of glycosyltransferases within the Golgi and have identified the transmembrane domains of ␣(2,6)sialyltransferase, ␤(1,4)galactosyltransferase, and N-acetylglucosaminyltransferase I as playing a central role in their Golgi localization (5); however, cytoplasmic tail and stem region sequences in ␣(2,6)sialyltransferase and Nacetylglucosaminyltransferase I also contain important structural elements within their cytoplasmic domains that augment the efficiency of Golgi localization of these proteins (5). Thus the sequences that localize glycosyltransferases within di...

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Section: Discussionmentioning

confidence: 99%

Switching Amino-terminal Cytoplasmic Domains of α(1,2)Fucosyltransferase and α(1,3)Galactosyltransferase Alters the Expression of H Substance and Galα(1,3)Gal

Osman

McKenzie

Mouhtouris

et al. 1996

Journal of Biological Chemistry

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“…Enzyme activity assay for a(1,6)FT a(1,6)FT activity was determined using a modification of the method described by Hartel-Schenk et al, 21 using asialo-agalactofetuin (ASAGF) as exogenous acceptor. The commercial fetuin (Sigma, St. Louis, MO) was desialylated and degalactosylated as described by Ko and Raguppathy 22 to obtain the ASAGF.…”

Section: Preparation Of Tissue Extractsmentioning

confidence: 99%

Expression and enzyme activity of α(1,6)fucosyltransferase in human colorectal cancer

Muinelo-Romay

Vázquez-Martín

Villar-Portela

et al. 2008

Intl Journal of Cancer

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Changes in enzyme activity and the expression levels of a(1,6)fucosyltransferase [a(1,6)FT] have been reported in certain types of malignant transformations. To develop a better understanding of the role of a(1,6)FT in human colorectal carcinoma (CRC), we analysed the enzyme activity in healthy and tumour tissues. a(1,6)FT activity was considerably higher in tumour tissue than in healthy tissue and was related to gender, lymph node metastasis, type of growth and tumour stage. We also observed a significant increase in the a(1,6)FT expression in tumour tissues as compared to healthy and transitional tissues, inflammatory lesions and adenomas. The immunohistochemical expression in tumour tissues was correlated with the degree of infiltration through the intestinal wall. Finally, a statistical correlation was found between enzyme activity and expression obtained by Western blot in colorectal tumours when compared in the same patient. All these findings demonstrate an alteration of a(1,6)FT activity and expression in CRC. ' 2008 Wiley-Liss, Inc.Key words: a(1,6)fucosyltransferase; FUT8; colorectal cancer It is well documented that N-linked oligosaccharides on glycoproteins are structurally altered during malignant transformation.

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“…Sialyltransferase activity was determined as previously described by Hartel-Schenk et al [18], with some modifications. In the standard assay, the reaction mixture had the following final concentrations in a total volume of 100 µl: 40 m M MES (pH 6.0), 4 m M NaF, 5 m M MnCl 2 , 0.2% (v/v) Triton X-100, 0.67 µ M CMP-[ 14 C]-NeuAc, 6 µ M CMP-NeuAc, 0.32 mg ASF and 50 µg of enzyme solution.…”

Section: Methodsmentioning

confidence: 99%

Alterations of CMP-NeuAc:Asialofetuin Sialyltransferase Activities in Human Colorectal Adenocarcinoma

Vázquez-Martín

Gil‐Martín²,

Fernández-Briera³

2002

Oncology

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It has been reported that surface glycoconjugates in tumour cells have more complex and more heavily sialylated sugar chains in glycoproteins. Here, we analysed CMP-NeuAc:asialofetuin sialyltransferase activities in total cell membranes from colorectal cancer tissue with respect to normal adjacent tissue, finding enhanced sialyltransferase activities. Determination of the kinetic parameters for the donor substrate, CMP-NeuAc, revealed that the apparent K_m in tumour tissue was decreased as regards to the normal value. Furthermore, we failed to find any correlation between this activity and the characteristics of the samples such as the age or sex of the patient, or Dukes’ stage of the tumour. In order to know which sialyltransferase activity was altered, we studied the incorporation of NeuAc into N- and O-linked chains from asialofetuin. The results allow us to conclude that it is on N-linked chains where the activity is enhanced. With respect to α(2,3)- and α(2,6)-NeuAc linkages, we observed that enhanced activity in tumour tissues affects both linkages equally.

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Distribution of glycosyltransferases among Golgi apparatus subfractions from liver and hepatomas of the rat

Cited by 35 publications

References 41 publications

Switching Amino-terminal Cytoplasmic Domains of α(1,2)Fucosyltransferase and α(1,3)Galactosyltransferase Alters the Expression of H Substance and Galα(1,3)Gal

Switching Amino-terminal Cytoplasmic Domains of α(1,2)Fucosyltransferase and α(1,3)Galactosyltransferase Alters the Expression of H Substance and Galα(1,3)Gal

Expression and enzyme activity of α(1,6)fucosyltransferase in human colorectal cancer

Alterations of CMP-NeuAc:Asialofetuin Sialyltransferase Activities in Human Colorectal Adenocarcinoma

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