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441.
442.
Structure of pre-pro-von Willebrand factor and its expression in heterologous cells 总被引:30,自引:0,他引:30
D T Bonthron R I Handin R J Kaufman L C Wasley E C Orr L M Mitsock B Ewenstein J Loscalzo D Ginsburg S H Orkin 《Nature》1986,324(6094):270-273
Von Willebrand factor (vWF), a multifunctional haemostatic glycoprotein derived from endothelial cells and megakaryocytes, mediates platelet adhesion to injured subendothelium and binds coagulation factor VIII in the circulation. Native vWF is a disulphide-bonded homopolymer; the monomeric subunits, of apparent relative molecular mass (Mr) 220,000 (220K) are derived from an intracellular precursor estimated at 260-275K. Multimer assembly is preceded by the formation of dimers, linked near their C-termini, which then assemble into filamentous polymers. The importance of the removal of the large vWF pro-polypeptide during multimer assembly, and whether this or other stages of the complex post-translational processing require components specific to endothelial cells or megakaryocytes, is unknown. Here we report an analysis of the complete sequence of pre-pro-vWF and expression of the molecule in heterologous cells. The vWF precursor is composed of several repeated subdomains. When expressed in COS and CHO cells, it is cleaved and assembled into biologically active high relative molecular mass disulphide bonded multimers. This suggests that the information for assembly of this complex molecule resides largely within its primary structure. 相似文献
443.
Long-range colour-generating interactions across the retina 总被引:1,自引:0,他引:1
The existence of colour-generating interactions across the corpus callosum has recently been suggested from observations with a 'split-brain' patient, thus indicating long-range colour computations at the cortical level. Observations on induced colours described here suggest long-range colour computations at the retinal level. If a white surface surrounded by a particular colour is fixated for some time, the resulting after-image has two colours: the surround appears in complementary colour, whereas the white centre takes on the colour of the surround. The question of whether such colour induction is located in the retina or more centrally was tested in a brain-injured patient with hemianopia. It could be demonstrated that areas of the visual field that are no longer represented in the geniculo-striatal pathway still contribute to colour induction, suggesting that colour induction is a retinal phenomenon. 相似文献
444.
Streptozotocin-diabetes in rats leads to a decrease of cytochrome P-450 UT-A (the major form in control rats) and an increase of cytochrome P-450 PB-B (the major one induced by phenobarbital treatment) in liver microsomes. The increased benzphetamine-N-demethylase activity can be related to the induction of cytochrome P-450 PB-B. 相似文献
445.
446.
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448.
Summary The effect of intraperitonal cycloheximide administration on acid-soluble rat liver chromatin proteins has been investigated by electrophoresis in acetic acid-urea polyacrylamide gels. A nonhistone protein, which migrates between oxidized histone H3 and histone H1 has been found tobe increased in amount following cycloheximide treatment. This protein seems to be identical with semihistone protein H24 (uH2A). A possible relationship of uH2A to the inhibition of rRNA synthesis is discussed.This work was supported by the Turkish Scientific and Technical Research Council (TUBITAK) Project No. TAG 339 相似文献
449.
E. Bonilla M. Salazar J. Estevez H. Hernández P. Rangel 《Cellular and molecular life sciences : CMLS》1984,40(8):868-869
Summary After i.p. inoculation with the Guajira strain of Venezuelan equine encephalomyelitis virus a significant decrease in the density of (3H) spiroperidol binding sites in the striatum, midbrain and frontal cortex was observed. No changes in the affinity of the receptors could be demonstrated. This finding is compatible with neuronal degeneration caused by the viral infection.Acknowledgments. This work was partially supported by Condes-Luz and Fundacite-Zulia. Butaclamol isomers were a gift of Ayerst Laboratories, Montreal, Canada. 相似文献
450.
Comparative distribution of vasoactive intestinal polypeptide (VIP), substance P and PHI in the enteric sphincters of the cat 总被引:2,自引:0,他引:2
G P McGregor A E Bishop M A Blank N D Christofides Y Yiangou J M Polak S R Bloom 《Experientia》1984,40(5):469-471
In the feline gastrointestinal tract, the neuropeptides, substance P, VIP and PHI were investigated by specific radioimmunoassays and immunocytochemistry. The concentrations of all 3 peptides and the level of peptidergic innervation were significantly less in the anal sphincter than elsewhere, whereas no significant differences were seen between other sphincter and non-sphincter regions. 相似文献