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排序方式: 共有445条查询结果,搜索用时 15 毫秒
31.
32.
Lise Barbin Dieter H. Wolf 《Biochemical and biophysical research communications》2010,394(2):335-3861
The switch from gluconeogenesis to glycolysis in yeast has been shown to require ubiquitin-proteasome dependent elimination of the key enzyme fructose-1,6-bisphosphatase (FBPase). Prior to proteasomal degradation, polyubiquitination of the enzyme occurs via the ubiquitin-conjugating enzymes Ubc1, Ubc4, Ubc5 and Ubc8 in conjunction with a novel multi-subunit ubiquitin ligase, the Gid complex. As an additional machinery required for the catabolite degradation process, we identified the trimeric Cdc48Ufd1-Npl4 complex and the ubiquitin receptors Dsk2 and Rad23. We show that this machinery acts between polyubiquitination of FBPase and its degradation by the proteasome. 相似文献
33.
34.
Yoko Chiba ) Ryoma Kamikawa ) Kumiko Nakada-Tsukui ) Yumiko Saito-Nakano ) Tomoyoshi Nozaki ) 《The Journal of biological chemistry》2015,290(39):23960-23970
Phosphoenolpyruvate carboxykinase (PEPCK) is one of the pivotal enzymes that regulates the carbon flow of the central metabolism by fixing CO2 to phosphoenolpyruvate (PEP) to produce oxaloacetate or vice versa. Whereas ATP- and GTP-type PEPCKs have been well studied, and their protein identities are established, inorganic pyrophosphate (PPi)-type PEPCK (PPi-PEPCK) is poorly characterized. Despite extensive enzymological studies, its protein identity and encoding gene remain unknown. In this study, PPi-PEPCK has been identified for the first time from a eukaryotic human parasite, Entamoeba histolytica, by conventional purification and mass spectrometric identification of the native enzyme, followed by demonstration of its enzymatic activity. A homolog of the amebic PPi-PEPCK from an anaerobic bacterium Propionibacterium freudenreichii subsp. shermanii also exhibited PPi-PEPCK activity. The primary structure of PPi-PEPCK has no similarity to the functional homologs ATP/GTP-PEPCKs and PEP carboxylase, strongly suggesting that PPi-PEPCK arose independently from the other functional homologues and very likely has unique catalytic sites. PPi-PEPCK homologs were found in a variety of bacteria and some eukaryotes but not in archaea. The molecular identification of this long forgotten enzyme shows us the diversity and functional redundancy of enzymes involved in the central metabolism and can help us to understand the central metabolism more deeply. 相似文献
35.
Obesity and its associated complications, which can lead to the development of metabolic syndrome, are a worldwide major public health concern especially in developed countries where they have a very high prevalence. RIP140 is a nuclear coregulator with a pivotal role in controlling lipid and glucose metabolism. Genetically manipulated mice devoid of RIP140 are lean with increased oxygen consumption and are resistant to high-fat diet-induced obesity and hepatic steatosis with improved insulin sensitivity. Moreover, white adipocytes with targeted disruption of RIP140 express genes characteristic of brown fat including CIDEA and UCP1 while skeletal muscles show a shift in fibre type composition enriched in more oxidative fibres. Thus, RIP140 is a potential therapeutic target in metabolic disorders. In this article we will review the role of RIP140 in tissues relevant to the appearance and progression of the metabolic syndrome and discuss how the manipulation of RIP140 levels or activity might represent a therapeutic approach to combat obesity and associated metabolic disorders. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease. 相似文献
36.
C.?C.?Nievola J.?E.?Kraus L.?Freschi B.?M.?Souza H.?MercierEmail author 《In vitro cellular & developmental biology. Plant》2005,41(6):832-837
Summary
Ananas comosus (L.) Merr. var. Smooth Cayenne plants when grown in vitro under different temperature regimes developed as CAM or as C3 plants. The plants used in this study were developed from the lateral buds of the nodal etiolated stem explants cultured
on Murashige and Skoog medium for 3 mo. The cultures were maintained under a 16-h photoperiod for different thermoperiods.
With 28°C light/15°C dark thermoperiod, as compared with constant 28°C light and dark, pineapple plants had a succulence index
two times greater, and also a greater nocturnal titratable acidity and phosphoenolpyruvate carboxylase (PEPCase) activity,
indicating CAM-type photosynthesis. The highest abscisic acid (ABA) level occurred during the light period, 8 h prior to maximum
PEPCase activity, while the indole-3-acetic acid (IAA) peak was found during the dark period, coinciding with the time of
highest PEPCase activity. These plants were also smaller with thicker leaves and fewer roots, but had greater dry weight.
Their leaves showed histological characteristics of CAM plants, such as the presence of greater quantities of chlorenchyma
and hypoderm. In addition, their vascular system was more conspicuous. In contrast, under constant temperature (28°C light/dark)
plants showed little succulence in the leaves. There was no significant acid oscillation and diurnal variation in PEPCase
activity in these plants, suggesting the occurrence of C3 photosynthesis. Also, no diurnal variation in ABA and IAA contents was observed. The results of this study clearly indicate
a role for temperature in determining the type of carbon fixation pathway in in vitro grown pineapple. Evidence that ABA and IAA participate in CAM signaling is provided. 相似文献
37.
Cariou B van Harmelen K Duran-Sandoval D van Dijk T Grefhorst A Bouchaert E Fruchart JC Gonzalez FJ Kuipers F Staels B 《FEBS letters》2005,579(19):4076-4080
The farnesoid X receptor (FXR) has been suggested to play a role in gluconeogenesis. To determine whether FXR modulates the response to fasting in vivo, FXR-deficient (FXR−/−) and wild-type mice were submitted to fasting for 48 h. Our results demonstrate that FXR modulates the kinetics of alterations of glucose homeostasis during fasting, with FXR−/− mice displaying an early, accelerated hypoglycaemia response. Basal hepatic glucose production rate was lower in FXR−/− mice, together with a decrease in hepatic glycogen content. Moreover, hepatic PEPCK gene expression was transiently lower in FXR−/−mice after 6 h of fasting and was decreased in FXR−/−hepatocytes. FXR therefore plays an unexpected role in the control of fuel availability upon fasting. 相似文献
38.
39.
We determined the kinetics of the reaction of human neuronal enolase and yeast enolase 1 with the slowly-reacting chromophoric substrate d-tartronate semialdehyde phosphate (TSP), each in tris (tris (hydroxymethyl) aminomethane) and another buffer at several Mg2+ concentrations, 50 or 100 μM, 1 mM and 30 mM. All data were biphasic, and could be satisfactorily fit, assuming either two successive first-order reactions or two independent first-order reactions. Higher Mg2+ concentrations reduce the relative magnitude of the slower reaction. The results are interpreted in terms of a catalytically significant interaction between the two subunits of these enzymes. 相似文献
40.
Aquaporins are channels that allow the movement of water across the cell membrane. Some members of the aquaporin family, the aquaglyceroporins, also allow the transport of glycerol, which is involved in the biosynthesis of triglycerides and the maintenance of fasting glucose levels. Aquaporin-7 (AQP7) is a glycerol channel mainly expressed in adipocytes. The deletion of AQP7 gene in mice leads to obesity and type 2 diabetes. AQP7 modulates adipocyte glycerol permeability thereby controlling triglyceride accumulation and fat cell size. Furthermore, the coordinated regulation of fat-specific AQP7 and liver-specific AQP9 may be key to determine glucose metabolism in insulin resistance. 相似文献