934 resultados para Sting apparatus
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Vorbesitzer: Bartholomaeusstift Frankfurt am Main
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subministravit Ioh Gottlob Carpzov
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This invention relates generally to grain threshing apparatus and in particular to an apparatus for threshing grain wherein an impeller is rotatable within a concave or tubular screen. This application is a division of application Serial No. 560,552, now Patent No. 2,906,270. An object of this invention is to provide an improved apparatus for threshing grain.
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Fecha de imp. del colofón 1602
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Pie de imp. tomado del colofón en D10v y F6r
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Marca tip. en port
A Role for Tlg1p in the Transport of Proteins within the Golgi Apparatus of Saccharomyces cerevisiae
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Members of the syntaxin protein family participate in the docking–fusion step of several intracellular vesicular transport events. Tlg1p has been identified as a nonessential protein required for efficient endocytosis as well as the maintenance of normal levels of trans-Golgi network proteins. In this study we independently describe Tlg1p as an essential protein required for cell viability. Depletion of Tlg1p in vivo causes a defect in the transport of the vacuolar protein carboxypeptidase Y through the early Golgi. Temperature-sensitive (ts) mutants of Tlg1p also accumulate the endoplasmic reticulum/cis-Golgi form of carboxypeptidase Y at the nonpermissive temperature (38°C) and exhibit underglycosylation of secreted invertase. Overexpression of Tlg1p complements the growth defect of vti1-11 at the nonpermissive temperature, whereas incomplete complementation was observed with vti1-1, further suggesting a role for Tlg1p in the Golgi apparatus. Overexpression of Sed5p decreases the viability of tlg1 ts mutants compared with wild-type cells, suggesting that tlg1 ts mutants are more susceptible to elevated levels of Sed5p. Tlg1p is able to bind His6-tagged Sec17p (yeast α-SNAP) in a dose-dependent manner and enters into a SNARE complex with Vti1p, Tlg2p, and Vps45p. Morphological analyses by electron microscopy reveal that cells depleted of Tlg1p or tlg1 ts mutants incubated at the restrictive temperature accumulate 40- to 50-nm vesicles and experience fragmentation of the vacuole.
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Biogenesis of the flagellum, a motive organelle of many bacterial species, is best understood for members of the Enterobacteriaceae. The flagellum is a heterooligomeric structure that protrudes from the surface of the cell. Its assembly initially involves the synthesis of a dedicated protein export apparatus that subsequently transports other flagellar proteins by a type III mechanism from the cytoplasm to the outer surface of the cell, where oligomerization occurs. In this study, the flagellum export apparatus was shown to function also as a secretion system for the transport of several extracellular proteins in the pathogenic bacterium Yersinia enterocolitica. One of the proteins exported by the flagellar secretion system was the virulence-associated phospholipase, YplA. These results suggest type III protein secretion by the flagellar system may be a general mechanism for the transport of proteins that influence bacterial–host interactions.
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The α- and β-karyopherins (Kaps), also called importins, mediate the nuclear transport of proteins. All α-Kaps contain a central domain composed of eight approximately 40 amino acid, tandemly arranged, armadillo-like (Arm) repeats. The number and order of these repeats have not changed since the common origin of fungi, plants, and mammals. Phylogenetic analysis suggests that the various α-Kaps fall into two groups, α1 and α2. Whereas animals encode both types, the yeast genome encodes only an α1-Kap. The β-Kaps are characterized by 14–15 tandemly arranged HEAT motifs. We show that the Arm repeats of α-Kaps and the HEAT motifs of β-Kaps are similar, suggesting that the α-Kaps and β-Kaps (and for that matter, all Arm and HEAT repeat-containing proteins) are members of the same protein superfamily. Phylogenetic analysis indicates that there are at least three major groups of β-Kaps, consistent with their proposed cargo specificities. We present a model in which an α-independent β-Kap progenitor gave rise to the α-dependent β-Kaps and the α-Kaps.
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Glycolipid glycosyltransferases catalyze the stepwise transfer of monosaccharides from sugar nucleotides to proper glycolipid acceptors. They are Golgi resident proteins that colocalize functionally in the organelle, but their intimate relationships are not known. Here, we show that the sequentially acting UDP-GalNAc:lactosylceramide/GM3/GD3 β-1,4-N-acetyl-galactosaminyltransferase and the UDP-Gal:GA2/GM2/GD2 β-1,3-galactosyltransferase associate physically in the distal Golgi. Immunoprecipitation of the respective epitope-tagged versions expressed in transfected CHO-K1 cells resulted in their mutual coimmunoprecipitation. The immunocomplexes efficiently catalyze the two transfer steps leading to the synthesis of GM1 from exogenous GM3 in the presence of UDP-GalNAc and UDP-Gal. The N-terminal domains (cytosolic tail, transmembrane domain, and few amino acids of the stem region) of both enzymes are involved in the interaction because (i) they reproduce the coimmunoprecipitation behavior of the full-length enzymes, (ii) they compete with the full-length counterpart in both coimmunoprecipitation and GM1 synthesis experiments, and (iii) fused to the cyan and yellow fluorescent proteins, they localize these proteins to the Golgi membranes in an association close enough as to allow fluorescence resonance energy transfer between them. We suggest that these associations may improve the efficiency of glycolipid synthesis by channeling the intermediates from the position of product to the position of acceptor along the transfer steps.
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Analysis of the mRNA capping apparatus of the malaria parasite Plasmodium falciparum illuminates an evolutionary connection to fungi rather than metazoans. We show that P. falciparum encodes separate RNA guanylyltransferase (Pgt1) and RNA triphosphatase (Prt1) enzymes and that the triphosphatase component is a member of the fungal/viral family of metal-dependent phosphohydrolases, which are structurally and mechanistically unrelated to the cysteine-phosphatase-type RNA triphosphatases found in metazoans and plants. These results highlight the potential for discovery of mechanism-based antimalarial drugs designed to specifically block the capping of Plasmodium mRNAs. A simple heuristic scheme of eukaryotic phylogeny is suggested based on the structure and physical linkage of the triphosphatase and guanylyltransferase enzymes that catalyze cap formation.