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51.
Bastepe M Gunes Y Perez-Villamil B Hunzelman J Weinstein LS Jüppner H 《Molecular endocrinology (Baltimore, Md.)》2002,16(8):1912-1919
XLalpha(s), the large variant of the stimulatory G protein alpha subunit (Gsalpha), is derived from GNAS1 through the use of an alternative first exon and promoter. Gs(alpha) and XLalpha(s) have distinct amino-terminal domains, but are identical over the carboxyl-terminal portion encoded by exons 2-13. XLalpha(s) can mimic some functions of Gs(alpha), including betagamma interaction and adenylyl cyclase stimulation. However, previous attempts to demonstrate coupling of XLalpha(s) to typically Gs-coupled receptors have not been successful. We now report the generation of murine cell lines that carry homozygous disruption of Gnas exon 2, and are therefore null for endogenous XLalpha(s) and Gs(alpha) (Gnas(E2-/E2-)). Gnas(E2-/E2-) cells transfected with plasmids encoding XLalpha(s) and different heptahelical receptors, including the beta2-adrenergic receptor and receptors for PTH, TSH, and CRF, showed agonist-mediated cAMP accumulation that was indistinguishable from that observed with cells transiently coexpressing Gs(alpha) and these receptors. Our findings thus indicate that XLalpha(s) is capable of functionally coupling to receptors that normally act via Gs(alpha). 相似文献
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Croute F Poinsot J Gaubin Y Beau B Simon V Murat JC Soleilhavoup JP 《Biochimica et biophysica acta》2002,1591(1-3):147-155
The aim of this study was to determine whether overexpression of stress proteins (SPs) could be a sensitive biomarker for cell injury due to exposure to low doses of volatile organic compounds (VOCs) such as benzene, ethylbenzene, toluene, xylene, and chlorinated derivatives (ClB). Sublethal and cytotoxic threshold concentrations of the VOCs were determined by studying the growth rate of normal (fibroblasts) or tumor-derived human cell lines (A549, HepG2) exposed for 4 days to VOCs. Changes in SP expression as a function of concentrations were investigated by Western blotting.VOC toxicity was found to be correlated with their degree of chlorination and their hydrophobicity. Cytotoxic threshold concentrations (no-observed effect concentration, NOEC) were found to be similar for the three cell lines. It was observed that using a mixture of VOCs, each of them at concentration below the NOEC, resulted in an actual toxicity to the cells. This finding reveals a synergistic effect and should be taken into account when assessing threshold risk and exposure limit values in the worker's environment when several pollutants may be present. HSP72 and HSP90 expression levels were not affected whereas GRP78 expression was increased by all the VOCs. Taking into account the specific molecular function of GRP78, it suggests that VOC exposure results in misfolded or underglycosylated protein accumulation in the endoplasmic reticulum. GRP78 overexpression was closely related to the magnitude of growth inhibition due to increasing concentrations of each VOC. The overexpression was found to be significant for concentrations 5 to 30 times higher than NOEC, indicating that, under our experimental conditions, GRP78 expression cannot be considered as a sensitive biomarker of exposure to environmental VOCs. 相似文献
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Theresa Pohlkamp Murat Durakoglugil Courtney Lane-Donovan Xunde Xian Eric B. Johnson Robert E. Hammer Joachim Herz 《PloS one》2015,10(2)
Apolipoprotein E (ApoE) genotype is the strongest predictor of Alzheimer’s Disease (AD) risk. ApoE is a cholesterol transport protein that binds to members of the Low-Density Lipoprotein (LDL) Receptor family, which includes LDL Receptor Related Protein 4 (Lrp4). Lrp4, together with one of its ligands Agrin and its co-receptors Muscle Specific Kinase (MuSK) and Amyloid Precursor Protein (APP), regulates neuromuscular junction (NMJ) formation. All four proteins are also expressed in the adult brain, and APP, MuSK, and Agrin are required for normal synapse function in the CNS. Here, we show that Lrp4 is also required for normal hippocampal plasticity. In contrast to the closely related Lrp8/Apoer2, the intracellular domain of Lrp4 does not appear to be necessary for normal expression and maintenance of long-term potentiation at central synapses or for the formation and maintenance of peripheral NMJs. However, it does play a role in limb development. 相似文献
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In this study, mainly biological treatment of prawn waste for chitin production was investigated. Lactic acid and protease
fermentations were applied to extract chitin from prawn waste in the presence of various glucose concentrations. The results
obtained were also compared with those of chemical method which was consisted of first mineral removal and then protein removal
sequence. Different strategies were applied using lactic acid producing bacterium, Lactococcus lactis, and a protease producer, marine bacterium Teredinobacter turnirae. Both bacteria were first cultivated individually and then cofermented. In their individual cultivation, L. lactis removed the inorganic materials efficiently, while T. turnirae performed better in deproteinization process. Cofermentation of both bacteria was also conducted using three different protocols.
The highest process yield (95.5%) was obtained when T. turnirae was first inoculated. Although the extraction of chitin by biological treatment was incomplete compared to the chemical method,
the biological treatment employed here could still be considered as an alternative method in a more environmentally benign
approach. 相似文献