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91.
SV40 large T antigen has been reported to be modified with several
different sugars including N-acetylglucosamine, galactose, and mannose. In
this report we have reexamined the glycosylation of T antigen and found
that while we could detect modification with N-acetylglucosamine, we could
not detect any other sugars on the protein. Surprisingly, even though
[3H]galactose could be metabolically incorporated into the protein,
analysis showed that all of the radioactivity in T antigen had been
converted to other species. The N-acetylglucosamine was demonstrated to be
linked to the protein in the form of O-linked N- acetylglucosamine, the
best characterized form of nuclear and cytoplasmic glycosylation in
mammalian systems. We have localized the major site of glycosylation to the
amino terminal portion of the molecule. Analysis of mutated T antigen where
serines 111/112 were substituted with alanine suggest that these residues
constitute a glycosylation site on the protein. These two serines fall
within a typical O-linked N-acetylglucosamine glycosylation site (PSS) and
are also known to be phosphorylated. Thus, it is likely that competition
between phosphorylation and glycosylation occurs at this site.
相似文献
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VK Satya R Radhajeyalakshmi K Kavitha V Paranidharan R Bhaskaran 《Archives Of Phytopathology And Plant Protection》2013,46(3):185-192
The fungitoxic effect of various medicinal plants belonging to different families was evaluated in vitro on Rhizoctonia solani, the rice sheath blight pathogen. Of the various plant extracts, the leaf extract of zimmu (Allium cepa × Allium sativum) showed the maximum antifungal activity against R. solani and recorded an inhibition zone of 12?mm. The leaf extract of zimmu was also effective in inhibiting the growth of other agronomically important fungal and bacterial pathogens viz., Aspergillus flavus, Curvularia lunata, Alternaria solani, Xanthomonas oryzae pv. oryzae, Xanthomonas campestris pv. malvacearum and Xanthomonas axonopodis pv. citri. The antimicrobial compound was dissoluble in methanol and the methanolic extract showed the absorption maxima at 210?nm and 230?nm. Phenolic compounds were present in greater amounts in methanol extract of zimmu. TLC analysis showed the appearance of two blue spots at R f ?=?0.65 and R f ?=?0.90. The compounds eluted at R f ?=?0.65 and R f ?=?0.90 by preparative TLC exhibited strong antifungal activity against R. solani. 相似文献
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95.
Muralidharan Suganthi Gopalakrishnan Sangeetha Govindaraj Gayathri Bhaskaran Ravi Sankar 《Biological trace element research》2012,150(1-3):477-486
Lithium, the first element of Group I in the periodic system, is used to treat bipolar psychiatric disorders. Lithium chloride (LiCl) is a selective inhibitor of glycogen synthase kinase-3?? (GSK-3??), a serine/threonine kinase that regulates many cellular processes, in addition to its role in the regulation of glycogen synthase. GSK-3?? is emerged as a promising drug target for various neurological diseases, type-2 diabetes, cancer, and inflammation. Several works have demonstrated that lithium can either inhibit or stimulate growth of normal and cancer cells. Hence, the present study is focused to analyze the underlying mechanisms that dictate the biphasic oncogenic properties of LiCl. In the current study, we have investigated the dose-dependent effects of LiCl on human breast cancer cells (MCF-7) by assessing the consequences on cytotoxicity and protein expressions of signaling molecules crucial for the maintenance of cell survival. The results showed breast cancer cells respond in a diverse manner to LiCl, i.e., at lower concentrations (1, 5, and 10?mM), LiCl induces cell survival by inhibiting apoptosis through regulation of GSK-3??, caspase-2, Bax, and cleaved caspase-7 and by activating anti-apoptotic proteins (Akt, ??-catenin, Bcl-2, and cyclin D1). In contrast, at high concentrations (50 and 100?mM), it induces apoptosis by reversing these effects. Moreover, LiCl also alters the sodium and potassium levels thereby altering the membrane potential of MCF-7 cells. Thus it is inferred that LiCl exerts a dose-dependent biphasic effect on breast cancer cells (MCF-7) by altering the apoptotic/anti-apoptotic balance. 相似文献
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R. Bhaskaran Nair P.A. Kurup 《Biochimica et Biophysica Acta (BBA)/General Subjects》1975,381(1):165-174
The enzymes from the venom of Heterometrus scaber, the indole compounds present and the toxic protein of the venom have been studied. The venom contains acid phosphatase, ribonuclease, 5′-nucleotidase, hyaluronidase, acetylcholine esterase and phospholipase A. The indole compounds present in the venom have been identified as 5-hydroxytryptophan, tryptophan, serotonin and tryptamine, along with two unidentified indole compounds. The venom produces hyperglycaemia in sublethal doses and this has been found to be due to increased adrenaline secretion. The toxic protein of the venom has been obtained in a pure form by (NH4)2 SO4 fractionation, followed by fractional precipitation with acetone and chromatography over DEAE-Sephadex. The toxic fraction has been found to be homogeneous on acrylamide gel electrophoresis. It is a glycoprotein (molecular weight 15 000) containing 1.74% glucosamine, 0.87% galactosamine, 0.313% sialic acid, 3.25% fucose and 0.45% of an unidentified neutral sugar. It did not show any enzyme activities, haemolytic activity or inhibition of succinate dehydrogenase activity but it produced hyperglycaemia in sublethal doses. The toxic level (intravenous administration in rats) was found to be 0.72 mg/kg body weight. 相似文献
98.
The lateral hypothalamus has an important role in regulating food and water intake. We have investigated the endogenous release of monoamines from the lateral hypothalamus during manipulations of plasma osmolality and circulating volume. Adult male Sprague-Dawley rats implanted with carbon paste in vivo electrochemical (EC) electrodes in the lateral hypothalamus were placed on a 72-h water deprivation schedule. Although the carbon paste EC electrode has an intrinsically ambiguous signal in which changes in ascorbic acid may appear as changes in catechol concentrations, pharmacologic studies in lateral hypothalamus indicated that the electrode most likely measured norepinephrine and possibly epinephrine. On the test day, the EC electrodes were scanned with linear sweep voltammetry from -0.2 to +0.4 V at a rate of 5 mV/s. Semiderivative signal processing showed catechol and hydroxyindole peaks at +0.11 and +0.23 V, respectively. Baseline recordings were made prior to rats drinking distilled water, 10% sucrose, 5% dextrose, 0.30% NaCl, 0.90% NaCl, or 10% d-mannitol. To control for the act of drinking, other implanted dehydrated rats were intraperitoneally injected with 5% dextrose, 0.30% NaCl, or 0.90% NaCl. To dissociate the effects of osmolality and circulating volume on the EC response, hydrated rats implanted with EC electrodes were subcutaneously injected with 12% NaCl or intraperitoneally injected with 35% polyethylene glycol. Other rats subjected to water deprivation and osmotic challenges were decapitated and trunk blood was collected for measurements of plasma osmolality and hematocrit. Similar experiments were conducted using homozygous Brattleboro rats which lack arginine vasopressin (AVP) but which preserve normal plasma osmolality with prodigious drinking.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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100.