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121.
122.
Release of the cellular prion protein from cultured cells after loss of its glycoinositol phospholipid anchor 总被引:3,自引:0,他引:3
Borchelt David R.; Rogers Mark; Stahl Neil; Telling Glenn; Prusiner Stanley B. 《Glycobiology》1993,3(4):319-329
Secreted forms of the sialoglycoprotein designated cellularprion protein (PrPC) have been identified that cannot be explainedby alternative splicing. We report that secreted forms of PrPCderive from precursors that are bound to the plasma membraneby glycoinositol phospholipid (GPI) anchors. Secreted PrPC slowlyappeared in the culture medium of metabolically radiolabelledcells after incubations of 824 h. Digestion of nascentPrPC with phosphatidylinositol-specific phospholipase C (PIPLC)prevented the appearance of secreted PrPC. Secreted PrPc partitionedinto the aqueous phase of Triton X114 like PIPLC-releasedPrPC. While the Mr of PIPLC-released PrPC was reduced 24kDa after treatment with aqueous hydroflouric acid, which removesthe entire GPI anchor modification, the Mr of secreted PrPCwas unchanged. Both PIPLC-released and secreted PrPc were recognizedby antiserum raised against a synthetic C-terminal peptide correspondingto residues 220233 (amino acid 231 is the site of GPIattachment). We conclude that GPI-anchored PrPC is post-translationallyprocessed to remove most, if not all, of the GPI modificationand then shed into culture medium. Whether PrPC is shed afterproteolysis near the C-terminus remains to be established. Aminority of PrPC in normal Syrian hamster brain partitionedinto the aqueous phase of Triton X114 like shed PrPCsuggesting physiological significance. post-translational prion protein secretion sialoglycoprotein 相似文献
123.
Michael A. Poss Joyce A. Reid Charles A. Free W. Lynn Rogers Helen Weber Denis E. Ryono Tamara Dejneka Jack M. DeForrest Thomas L. Waldron Russell J. Brittain Harold N. Weller Maria P. Cimarusti Edward W. Petrillo 《Bioorganic & medicinal chemistry letters》1993,3(12):2739-2744
The syntheses and pharmacological activity of a series of diol sulfonamides which function as inhibitors of human renin are described. The most potent compound in this series, compound 20 (SQ 33,800), is a subnanomolar inhibitor of human renin (IC50 = 0.35 × 10−9 M). 相似文献
124.
C. S. Rogers 《Coral reefs (Online)》1993,12(3-4):127-137
A review of research on the effects of hurricanes on coral reefs suggests that the intermediate disturbance hypothesis may be applicable to shallow reef zones dominated by branching or foliaceous coral species that are especially susceptible to mechanical damage from storms. Diversity (H') increases because of an increase in evenness following destruction or removal of the species that was monopolizing the space. The intermediate disturbance hypothesis as presented by Connell focuses on changes in number of species, but should be expanded to include diversity (H') and evenness. It should also be modified to incorporate changes in living cover and the time elapsed since disturbances of varying intensities. This hypothesis predicts that when cover is high, diversity will be low. However, research on coral reefs does not consistently demonstrate an inverse correlation of coral diversity, and coral cover. An increase in cover and decrease in diversity with depth would also be expected because deeper reef zones generally experience less disturbance. However, higher diversity (both H' and species richness) is often associated with deeper zones. The effects of hurricanes on coral reefs will depend on the temporal and spatial scales under consideration, the life history characteristics and morphology of the dominant species, the depth of the reef zone, the ecological history of the site, and the influence of any additional natural or human stresses. 相似文献
125.
G Boissonneault J Gagnon M A Ho-Kim P A Rogers R R Tremblay 《Journal of steroid biochemistry》1989,32(4):507-513
The androgen-dependent levator ani (LA) muscle of the rat provides a suitable model to explore the molecular mechanism of steroid hormone action in target tissues. The objective of the present series of experiments was to study the effect of gonadectomy (GDX) and androgen replacement therapy on the in vitro protein synthetic capacity of the LA muscle. The incorporation of labeled methionine into the contractile protein fraction of the LA muscle maintained in organ culture decreases in a time-dependent manner following GDX. Translation of total polyadenylated mRNA in the rabbit reticulocyte translation system revealed that the decrease in protein synthetic capacity was not associated with differences in the template activity of the mRNA derived from GDX tissue. However, when polyribosomes were used to direct the same in vitro synthesis system, a significant time-dependent loss of translational activity was observed following GDX. The polyribosomes of the LA muscle of control and GDX rats were shown to contain equivalent amount of rRNA and mRNA of comparable translation efficiency. Collectively the results of these experiments indicate that the decrease in protein synthetic capacity of the LA muscle in androgen deficient rats is due, in part, to a repression of the translation process associated to the functional integrity of polyribosomes. 相似文献
126.
Sayan Mukherjee Pablo Tamayo Simon Rogers Ryan Rifkin Anna Engle Colin Campbell Todd R Golub Jill P Mesirov 《Journal of computational biology》2003,10(2):119-142
A statistical methodology for estimating dataset size requirements for classifying microarray data using learning curves is introduced. The goal is to use existing classification results to estimate dataset size requirements for future classification experiments and to evaluate the gain in accuracy and significance of classifiers built with additional data. The method is based on fitting inverse power-law models to construct empirical learning curves. It also includes a permutation test procedure to assess the statistical significance of classification performance for a given dataset size. This procedure is applied to several molecular classification problems representing a broad spectrum of levels of complexity. 相似文献
127.
H. B. Rogers C. A. Beyrouty T. D. Nichols D. C. Wolf C. M. Reynolds 《Soil & Sediment Contamination》1996,5(2):171-186
A mixture of organic chemicals (MOC) containing equal molar amounts of benzoic acid, hexadecane, 2,2‐dimethyl 4,n‐propyl‐benzene, phenanthrene, pyrene, and either cycloheptane or cis‐decahydronaphthalene (cis‐decalin) was applied to soil at rates of 0 to 8000 mg/kg. In a plant‐screening experiment, growth responses of four legume and five nonlegume species were determined at 10 and 25°C. The MOC applied at 2000 mg/kg reduced the growth of several species without resulting in significant seedling death. At 10°C, the growth of alpine bluegrass (Poa alpina L.) in the 1000 and 2000 mg/kg treatments of soil increased by more than 185%. In a plant growth response experiment, alpine bluegrass and alfalfa (Medicago sativa L.) were grown in soil that had been contaminated at rates of 0 and 2000 mg/kg. At 14 weeks, the shoot and root dry weights of alfalfa were 97% lower in the contaminated soil, while the shoot dry weight, root dry weight, and root length of alpine bluegrass were 135,235 and 268% higher, respectively. Except for pyrene, <23% of the compounds comprising the MOC remained in the soil after 4 weeks and <5% after 14 weeks. The disappearance of the MOC was not significantly influenced by the presence of alfalfa or alpine bluegrass. 相似文献
128.
129.
Swamp gorillas in northern Congo 总被引:3,自引:0,他引:3
130.
To provide further understanding of the biotransformation of benzaldehyde to L-phenylacetyl carbinol (L-PAC), an intermediate in L-ephedrine production, a kinetic model has been developed for the deactivation of pyruvate decarboxylase (PDC) by benzaldehyde. The model confirms that deactivation is first order with respect to benzaldehyde concentration and exhibits a square root dependency on time. The model covers the range of benzaldehyde concentrations 100–300 mM, as it has been shown previously that 200 mM benzaldehyde can produce L-PAC concentrations up to 190 mM (28.6 g/L) using partially purified PDC from Candida utilis. 相似文献