High-Pressure Pump Drive of the Common Rail Fuel-Supply System for a Diesel Locomotive Engine

Russian Engineering Research - A camshaft drive is developed for modular high-pressure pumps of the Common Rail fuel supply system in the 16FTN26/28 diesel locomotive.     

Trends in Russian research output in post-Soviet era

Recently, the Russian government has ordered evaluation and reform of the basic research system. As a consequence, the number of research staff at the Russian Academy of Sciences will be reduced by 20% by 2007. The basis for research evaluation and institute budgeting will be bibliometric indicators. In view of these changes we look at the Russian publication output and argue that

Analysis of a conditional degradation signal in yeast and mammalian cells

The N-end rule pathway is a ubiquitin-dependent proteolytic system, the targets of which include proteins that bear destabilizing N-terminal residues. The latter are a part of the degradation signal called the N-degron. Arg-DHFRts, an engineered N-end rule substrate, bears N-terminal arginine (a destabilizing residue) and DHFRts [a temperature-sensitive mouse dihydrofolate reductase (DHFR) moiety]. Previous work has shown that Arg-DHFRts is long-lived at 23 degreesC but short-lived at 37 degreesC in the yeast Saccharomyces cerevisiae. In the present work, we extended this analysis, and found that the degradation of Arg-DHFRts can be nearly completely inhibited in vivo by methotrexate (MTX), a low-Mr ligand of DHFR. In S. cerevisiae, Arg-DHFRts is degraded at 37 degreesC exclusively by the N-end rule pathway, whereas in mouse cells the same protein at the same temperature is also targeted by another proteolytic system, through a degron in the conformationally perturbed DHFRts moiety. In mouse cells, MTX completely inhibits the degradation of Arg-DHFRts through its degron within the DHFRts moiety, but only partially inhibits degradation through the N-degron. When the N-terminus of Arg-DHFRts was extended with a 42-residue lysine-lacking extension, termed eDeltaK, the resulting Arg-eDeltaK-DHFRts was rapidly degraded at both 23 degreesC and 37 degreesC. Moreover, the degradation of Arg-eDeltaK-DHFRts, in contrast with that of Arg-DHFRts, could not be inhibited by MTX, suggesting that the metabolic stability of Arg-DHFRts at 23 degreesC results, at least in part, from steric inaccessibility of its N-terminal arginine. The N-degron of Arg-DHFRts is the first example of a portable degradation signal the activity of which can be modulated in vivo by a cell-penetrating compound. We discuss implications of this advance and the mechanics of targeting by the ubiquitin system.     

The mouse and human genes encoding the recognition component of the N-end rule pathway

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. The N-end rule pathway is one proteolytic pathway of the ubiquitin system. The recognition component of this pathway, called N-recognin or E3, binds to a destabilizing N-terminal residue of a substrate protein and participates in the formation of a substrate-linked multiubiquitin chain. We report the cloning of the mouse and human Ubr1 cDNAs and genes that encode a mammalian N-recognin called E3alpha. Mouse UBR1p (E3alpha) is a 1,757-residue (200-kDa) protein that contains regions of sequence similarity to the 225-kDa Ubr1p of the yeast Saccharomyces cerevisiae. Mouse and human UBR1p have apparent homologs in other eukaryotes as well, thus defining a distinct family of proteins, the UBR family. The residues essential for substrate recognition by the yeast Ubr1p are conserved in the mouse UBR1p. The regions of similarity among the UBR family members include a putative zinc finger and RING-H2 finger, another zinc-binding domain. Ubr1 is located in the middle of mouse chromosome 2 and in the syntenic 15q15-q21.1 region of human chromosome 15. Mouse Ubr1 spans approximately 120 kilobases of genomic DNA and contains approximately 50 exons. Ubr1 is ubiquitously expressed in adults, with skeletal muscle and heart being the sites of highest expression. In mouse embryos, the Ubr1 expression is highest in the branchial arches and in the tail and limb buds. The cloning of Ubr1 makes possible the construction of Ubr1-lacking mouse strains, a prerequisite for the functional understanding of the mammalian N-end rule pathway.     

Organizing collective behaviour in the job distribution problem

A possibility of organizing a collective behaviour of executors, ensuring decentralized distribution of jobs in the process of production is being considered. As an example, a mechanical sector of a machine-building plant is being considered.     

Configuration of a Common Rail Fuel-Supply System for a Diesel Engine

Russian Engineering Research - The structure of an electrohydraulic fuel-supply system is developed. Its configuration in the promising 16FT26/28 diesel engine for railroad locomotives is proposed....     

Detection of transient in vivo interactions between substrate and transporter during protein translocation into the endoplasmic reticulum

The split-ubiquitin technique was used to detect transient protein interactions in living cells. Nub, the N-terminal half of ubiquitin (Ub), was fused to Sec62p, a component of the protein translocation machinery in the endoplasmic reticulum of Saccharomyces cerevisiae. Cub, the C-terminal half of Ub, was fused to the C terminus of a signal sequence. The reconstitution of a quasi-native Ub structure from the two halves of Ub, and the resulting cleavage by Ub-specific proteases at the C terminus of Cub, serve as a gauge of proximity between the two test proteins linked to Nub and Cub. Using this assay, we show that Sec62p is spatially close to the signal sequence of the prepro-alpha-factor in vivo. This proximity is confined to the nascent polypeptide chain immediately following the signal sequence. In addition, the extent of proximity depends on the nature of the signal sequence. Cub fusions that bore the signal sequence of invertase resulted in a much lower Ub reconstitution with Nub-Sec62p than otherwise identical test proteins bearing the signal sequence of prepro-alpha-factor. An inactive derivative of Sec62p failed to interact with signal sequences in this assay. These in vivo findings are consistent with Sec62p being part of a signal sequence-binding complex.     

Alternative splicing results in differential expression, activity, and localization of the two forms of arginyl-tRNA-protein transferase, a component of the N-end rule pathway

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. The underlying ubiquitin-dependent proteolytic system, called the N-end rule pathway, is organized hierarchically: N-terminal aspartate and glutamate (and also cysteine in metazoans) are secondary destabilizing residues, in that they function through their conjugation, by arginyl-tRNA-protein transferase (R-transferase), to arginine, a primary destabilizing residue. We isolated cDNA encoding the 516-residue mouse R-transferase, ATE1p, and found two species, termed Ate1-1 and Ate1-2. The Ate1 mRNAs are produced through a most unusual alternative splicing that retains one or the other of the two homologous 129-bp exons, which are adjacent in the mouse Ate1 gene. Human ATE1 also contains the alternative 129-bp exons, whereas the plant (Arabidopsis thaliana) and fly (Drosophila melanogaster) Ate1 genes encode a single form of ATE1p. A fusion of ATE1-1p with green fluorescent protein (GFP) is present in both the nucleus and the cytosol, whereas ATE1-2p-GFP is exclusively cytosolic. Mouse ATE1-1p and ATE1-2p were examined by expressing them in ate1Delta Saccharomyces cerevisiae in the presence of test substrates that included Asp-betagal (beta-galactosidase) and Cys-betagal. Both forms of the mouse R-transferase conferred instability on Asp-betagal (but not on Cys-betagal) through the arginylation of its N-terminal Asp, the ATE1-1p enzyme being more active than ATE1-2p. The ratio of Ate1-1 to Ate1-2 mRNA varies greatly among the mouse tissues; it is approximately 0.1 in the skeletal muscle, approximately 0.25 in the spleen, approximately 3.3 in the liver and brain, and approximately 10 in the testis, suggesting that the two R-transferases are functionally distinct.