Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.99.7 (sialyltransferase)
 1,534 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sialyltransferase-1 activity was studied in cultured 12-18 human glioma cells. The apparent Km and Vmax with variable LacCer concentrations were 32 microM and 197 pmoles/mg protein/hr and with variable CMP-NeuAc concentrations were 172 microM and 877 pmoles/mg protein/hr., respectively. The pH optimum towards exogenous LacCer was 6.0 and towards endogenous acceptors was 6.2. The optimum protein:detergent ratio was 1:1. Human beta interferon (1000 units/ml medium) increased sialyltransferase-1 activity only slightly on a protein basis but increased it 47% on a per cell basis. These results demonstrate that one of the biochemical effects of beta-interferon on 12-18 human glioma cells is to stimulate ganglioside synthesis.
J Neurooncol 1988 Sep
PMID:Sialyltransferase-1 in a human malignant glioma cell line. Kinetic characteristics and effect of human interferon-beta. 285 19

A rat brain Golgi sialyltransferase activity capable of the differentiation-dependent control of N-CAM sialylation state is described. The specific activity of Golgi sialyltransferase was found to be developmentally regulated with respect to both endogenous and exogenous protein acceptors, with a particular elevation on postnatal days 10-12 when the heavily sialylated or 'embryonic' form of N-CAM is re-expressed. The subsequent developmental decrease in activity was associated with a significant decrease in apparent Km for the CMP-NeuNAc substrate, but not for the asialofetuin exogenous acceptor, which could not be attributed to the temporal expression of an endogenous competitive inhibitor. The apparent Vmax remained constant for CMP-NeuNAc but was significantly reduced for asialofetuin. Sialyltransferase activity, which was optimal at pH 7.0-7.5, was also modulated by various cations. Zinc abolished enzyme function, in contrast to ferric ions which stimulated activity fourfold-sevenfold. The marked activation of the adult form of the enzyme by potassium and magnesium ions, together with the alterations in kinetic constants, suggested this activity to be distinct from that derived from postnatal day-12 tissue. The kinetics of [14C]sialic acid incorporation into immuno-precipitated N-CAM demonstrated the individual polypeptides to be sialylated, possibly by addition of polysialosyl units, in a developmental sequence. The presence of four distinct sialyltransferase activities was demonstrated by non-denaturing gel electrophoresis followed by solid-phase enzyme assay. These isoforms were temporally expressed during development, two being correlated with the postnatal reexpression of the 'embryonic' form of N-CAM.
Development 1988 Sep
PMID:Developmental control of N-CAM sialylation state by Golgi sialyltransferase isoforms. 325 55

Influenza viruses of contrasting receptor specificity have been examined for their ability to infect receptor-modified MDCK cells containing sialyloligosaccharide receptor determinants of defined sequence. Cells were treated with sialidase to remove sialic acid and render them resistant to infection and were then incubated with sialyltransferase and CMP-sialic acid to restore sialic acid in the SA alpha 2,6Gal or SA alpha 2,3Gal linkages. The viruses A/RI/5 + /57 and A/duck/Ukraine/1/63, previously shown to exhibit preferential binding of SA alpha 2,6Gal and SA alpha 2,3Gal linkages, respectively, were found to exhibit differential infection of the receptor-modified cells in accord with their receptor specificity. Coinfection of SA alpha 2,3Gal derivatized cells with a mixture of the two viruses resulted in selective propagation of the SA alpha 2,3Gal-specific A/duck/Ukraine/1/63 virus. The results demonstrate the potential for cell surface receptors to mediate selection of receptor-specific variants of influenza virus.
Virus Res 1985 Sep
PMID:Differential infection of receptor-modified host cells by receptor-specific influenza viruses. 406 Aug 86

Administration of thyrotropin to porcine thyroid follicles, obtained in a serum-free chemically defined medium, provoked marked increases in the activities of several glycosyltransferases involved in protein N-glycosylation. The coincidence of these effects with a previously demonstrated enhancement of thyroglobulin production renders a relationship between these events likely. The most important stimulation was for peptide oligosaccharyltransferase (3-fold). Among the enzymes involved in the synthesis of the lipid oligosaccharide donor, Dol-P glycosyl- and mannosyltransferases were increased 1.5-fold, and Dol-P N-acetylglucosaminylphosphotransferase only 1.15-fold. As regards terminal glycosyltransferases, asialofetuin sialyltransferase was increased 2-fold and ovomucoid galactosyltransferase only 1.2-fold. There was a continuous release of the latter two enzymes into the culture medium.
Mol Cell Endocrinol 1984 Sep
PMID:Responsiveness of glycosyltransferases to thyrotropin in a serum-free culture of porcine thyroid cells. 609 77

Sialyltransferase and 5'-nucleotidase were measured in the sera of 135 women with breast cancer: 53 undergoing mastectomy for primary cancer and 83 receiving different modalities of palliative therapy for metastatic disease. The objective of this study was to determine whether these enzyme levels were associated with the extent of the disease and whether changes in these enzyme levels could be correlated with success or failure of treatment. Mastectomy caused a rapid fall of elevated enzyme levels to within the normal range in all patients with stage I breast cancer but not in those with stage II or III disease. In women with metastatic disease, elevated enzyme levels fell only in patients responding to treatment. Thus serum sialyltransferase and 5'-nucleotidase activities are reliable biomarkers of breast cancer activity, and serial measurement of these enzyme activities provides a useful tool for the monitoring of disease activity and success or failure of the treatment.
J Natl Cancer Inst 1980 Sep
PMID:Serum sialyltransferase and 5'-nucleotidase as reliable biomarkers in women with breast cancer. 625 2

Highly purified rat brain myelin isolated by two different procedures showed appreciable activity for CDP-ethanolamine: 1,2-diacyl-sn-glycerol ethanolaminephosphotransferase (EC 2.7.8.1). Specific activity was close to that of total homogenate and approximately 12-16% that of brain microsomes. Three other lipid-synthesizing enzymes, cerebroside sulfotransferase, lactosylceramide sialyltransferase, and serine phospholipid exchange enzyme, were found to have less than 0.5% the specific activity in myelin compared with microsomes. Washing the myelin with buffered salt or taurocholate did not remove the phosphotransferase, but activity was lost from both myelin and microsomes by treatment with Triton X-100. It resembled the microsomal enzyme in having a pH optimum of 8.5 and a requirement for Mn2+ and detergent, but differed in showing no enhancement with EGTA. The diolein Km was similar for the two membranes (2.5-4 x 10(-4) M), but the CDP-ethanolamine Km was lower for myelin (3-4 x 10(-5) M) than for microsomes (11 - 13 x 10(-5 M). Evidence is reviewed that this enzyme is able to utilize substrate from the axon in situ.
J Neurochem 1980 Sep
PMID:Evidence for the presence of CDP-ethanolamine: 1,2-diacyl-sn-glycerol ethanolaminephosphotransferase in rat central nervous system myelin. 625 94

In regenerating rat liver the activities of CMP-N-acetylneuraminate hydrolase and UDP-galactose pyrophosphatase were decreased to 40-50% of control values within 35 h after partial hepatectomy. In the same time period the activities of sialyltransferase and galactosyltransferase were increased, and the initial sharp decrease in the carbohydrate content of liver and serum glycoproteins was largely restored. The antiparallel nature of these events is suggestive of an involvement of nucleotide-sugar-hydrolysis enzymes in rat liver glycoprotein biosynthesis.
Biochem J 1983 Sep 15
PMID:Increased glycosylation capacity in regenerating rat liver is paralleled by decreased activities of CMP-N-acetylneuraminate hydrolase and UDP-galactose pyrophosphatase. 631 60

We have assayed glycosyltransferase activities during the granulocytic and macrophage-like differentiation of human promyelocytic leukemia (HL-60) cells. Functional granulocytic differentiation was assayed by the decarboxylation of 2-deoxyglucose in addition to nitroblue tetrazolium reduction. Dimethylsulfoxide (DMSO) treated HL-60 cells, induced to granulocytic differentiation, had higher 2-deoxy-glucose decarboxylation activity, and contained less sialyltransferase (ST), more fucosyltransferase (FT), and more N-acetylglucosaminyltransferase (NGT) activities than untreated cells. HL-60 cells treated with another granulocytic differentiator, retinoic acid, also had higher 2-deoxyglucose decarboxylation activity, and contained less ST, more FT, and more NGT activities than untreated cells. In contrast, cells treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) reported to differentiate HL-60 to macrophage-like cells, but did not show an increased level of 2-deoxyglucose decarboxylation activity, but contained more galactosyltransferase (GT) and FT activities as compared to untreated cells. These findings suggest that the alterations of glycosyltransferase levels during the differentiation of precursor cells may not depend upon different inducers, but are characteristic of the phenotypic expression of the mature cell type.
Exp Hematol 1983 Sep
PMID:Glycosyltransferase alterations are cell type related when human promyelocytic leukemia (HL-60) cells are treated with various inducers of differentiation. 641 38

The effect of phorbol esters on ganglioside metabolism in contact-inhibited Chinese hamster V79 cells was examined. Three phorbol esters of varying structure and tumor-promoting activity were used. Treatment of cells with tumor-promoting phorbol esters resulted in accumulation of gangliosides and increased incorporation of [1-14C]palmitate and [9-3H]sialic acid into gangliosides. Moreover, the phorbol esters were found to increase the activity of CMP-sialic acid: lactosylceramide sialyltransferase, the enzyme catalysing the first step in ganglioside biosynthesis. The magnitude of phorbol ester effects on V79 cell ganglioside metabolism correlated with the in vivo phorbol ester tumor-promoting activity.
Exp Cell Res 1983 Sep
PMID:Phorbol ester-associated changes in ganglioside metabolism. 657 51

The total sialic (N-acetylneuraminic acid) levels were serially determined in maternal plasma, urine and lymphocytes during human pregnancy and post-partum period. The enzymes, sialyltransferase and neuraminidase, were also examined in the plasma samples. The sialic acid content of plasma and urine (expressed in terms of the creatinine content in urine) was elevated during pregnancy and increased with advancing gestation (P less than 0.001). A few days (0-6) prior to parturition there was a significant (P less than 0.01) fall in the plasma sialic acid levels, which subsequently increased again in the post-partum period (1-14 days), reaching values even greater than that observed during pregnancy. On the other hand, there was no decrease in the urinary sialic acid levels before delivery, and the post-partum values in urine, though higher than the values obtained in non-pregnant women, were not significantly greater than the levels observed during pregnancy. The sialic acid levels in lymphocytes were not altered during pregnancy. There was also no statistically significant change in serum sialyltransferase activity at any stage of pregnancy or post-partum period, while neuraminidase was not detectable in any of the plasma samples. The results are discussed with reference to the role of circulating sialic acid during pregnancy.
Eur J Obstet Gynecol Reprod Biol 1983 Sep
PMID:Sialic acid, sialyltransferase and neuraminidase levels in maternal plasma, urine and lymphocytes during pregnancy and post-partum period--a longitudinal study in women. 662 18


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