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Catherine Ronin Herman van Halbeek Johannah GM Mutsaers Johannes F G Vliegenthart 《Glycoconjugate journal》1987,4(3):247-254
The lipid-linked precursor ofN-type glycoprotein oligosaccharides was isolated from porcine thyroid microsomes after in cubation with UDP[3H] Glucose. The carbohydrate was released from dolichol pyrophosphate by mild acid hydrolysis, purified by gel filtration and characterized by 500-MHz1H-NMR spectroscopy in combination with enzymatic degradation. The parent oligosaccharide was found to be Glc3Man9Glc-NAc2. The three glucose residues are present in the linear sequence Glcα1-2Glα1-3 Glc, the latter being α(1-3)-linked to one of the mannose residues. In order to establish the branch location of the triglucosyl unit, the parent compound was digested with jack-bean α-mannosidase. The oligosaccharide product was purified by gel filtration, and identified by1H-NMR as Glc3Man5GlcNAc2 lacking the mannose residues A, D2, B and D3. Therefore, the structure of the precursor oligosaccharide is as follows: $$\begin{gathered} c b a D_1 C 4 \hfill \\ Glc\alpha 1 - 2Glc\alpha 1 - 3Glc\alpha 1 - 3Man\alpha 1 - 2Man\alpha 1 - 2Man\alpha 1 \hfill \\ 3 \swarrow 3 2 1 \hfill \\ Man\alpha 1 - 2Man\alpha 1 Man\beta 1 - 4GlcNAc\beta 1 - 4GlcNAc \hfill \\ D_{2 } A 3 6 \hfill \\ Man\alpha 1 \hfill \\ 6 \hfill \\ Man\alpha 1 - 2Man\alpha 1 \nwarrow 4 \hfill \\ D_3 B \hfill \\ \end{gathered} $$ 相似文献
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Metabolism of synthetic inositol trisphosphate analogs 总被引:2,自引:0,他引:2
M A Polokoff G H Bencen J P Vacca S J deSolms S D Young J R Huff 《The Journal of biological chemistry》1988,263(24):11922-11927
A series of synthetic analogs was employed to explore structure-activity relationships in the metabolism of the second messenger inositol trisphosphate (IP3) in vascular tissue. Cytosolic IP3-5-phosphatase activity was purified approximately 240-fold from bovine aorta. All synthetic analogs tested were apparent competitive inhibitors of the 5-phosphatase activity. The order of potency was DL-1,3,4,5-IP3 greater than D-1,4,5-IP3 greater than DL-1,3,4-IP3 greater than L-1,4,5-IP3 greater than 1,3,5-IP3 greater than DL-6-methoxy-1,4,5-IP3 greater than DL-2,4,5-IP3 greater than DL-1,2,4-cyclohexane-P3. The least potent analogs had Ki values only 11 times higher than the apparent Km of the substrate D-1,4,5-[3H]IP3. However, only three synthetic compounds, DL-1,3,4,5-IP4, D-1,4,5-IP3, and DL-2,4,5-IP3, could serve as substrates for the 5-phosphatase. IP3 kinase activity in the same tissue exhibited considerably more selectivity with respect to inhibition by IP3 analogs. D-1,4,5-IP3 was about 30 times more potent than DL-1,3,4,5-IP4 and 100-1000 times more potent than the other compounds tested. The function of the IP3 receptor was evaluated by measuring labeled calcium mobilization in permeabilized bovine aortic smooth muscle cells in culture. While all analogs tested were full agonists, vast differences in potency were observed. D-1,4,5-IP3 was about 30 times more potent than DL-2,4,5-IP3 and 100-2000 times more potent than the other analogs tested. The results suggest that IP3-5-phosphatase activity is relatively nonselective in the binding of inositol polyphosphates, while IP3 kinase activity and the IP3 receptor exhibit great selectivity in the recognition of these compounds. 相似文献
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E. Petrangeli C. Lubrano F. Ortolani L. Ravenna A. Vacca S. Sciacchitano L. Frati A. Gulino A. Vacca S. Sciacchitano L. Frati A. Gulino 《The Journal of steroid biochemistry and molecular biology》1994,49(4-6):327-331
The imbalance between proliferative and differentiative estrogenic effect, caused by quantitative and qualitative alteration of the estrogen receptor (ER) expression, may play a determinant role in mammary neoplastic transformation. Our studies demonstrate that ER levels are significantly higher in human mammary neoplastic tissues when compared to perineoplastic tissues and that increased ER expression is associated with ER gene hypomethylation. During progressive multifactorial carcinogene, ER overexpression may represent an early step in neoplastic transformation. In fact, high levels of ER represent good markers of differentiation and can predict the likelihood of benefiting from anti-estrogen therapy. Nevertheless, about 35% of ER-positive breast cancers are resistant to endocrine therapy and 10% of ER-negative tumors behave as hormone-sensitive tumors. Recent studies on ER mRNA variants, which naturally occur in human breast tumors, demonstrated mutations, deletions and alternative splicings, yielding deletions of exons 3, 4, 5 and 7. ER variants exhibited altered functions or changed the responsiveness to hormonal therapy. Analysis of these variants could be a useful parameter to better predict tumor responsiveness to anti-estrogen therapy. Recently, a regain of hormonal responsiveness by ER-negative breast cancer cells has been reported following ER gene transfection. However, estradiol treatment inhibits rather than stimulates cell growth as well as the metastatic and invasive potential of the ER gene transduced cells. Transfer of the ER gene may be considered as a new therapeutic approach in the management of hormone-independent breast cancer. 相似文献
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Ralph D. Lillie Patricia T. Donaldson Linda L. Vacca Philip P. Pizzolato Shitalkumar K. Jirge 《Histochemistry and cell biology》1977,51(2-3):141-152
Summary Cutaneous melanin in formol fixed skin and adrenochrome in dichromate fixed monkey adrenal after adequate bisulfite or dithonite reduction were found to give definite azo coupling reactions. Weaker reactions were obtained on unreduced material, and these disappeared on ferric chloride oxidation. Both cutaneous melanin and adrenochrome appear to exist in a quinhydrone status. Prolongation of dichromate treatment weakens or abolishes azo coupling capacity of adrenochrome. The findings support the concept of quinonization and reduction to prevent and restore azo coupling of enterochromaffin cells and noradrenaline islets of the adrenal.The most effective diazos for melanin werep-nitrodiazobenzene, fast black K and the diazosulfanilic acid, pH 1 pyronin B procedure, for adrenochrome. Diazosafranin and 2-chloro-4-nitrodiazobenzene were also useful. Blue and violet coupling products from toluidine blue and methylene violet RR fail to yield sufficient contrast to be convincing. 相似文献
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