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P Kolkhof D Teichmann B Kisters-Woike B von Wilcken-Bergmann B Müller-Hill 《The EMBO journal》1992,11(8):3031-3038
Lac repressor, lambda cro protein and their operator complexes are structurally, biochemically and genetically well analysed. Both proteins contain a helix-turn-helix (HTH) motif which they use to bind specifically to their operators. The DNA sequences 5'-GTGA-3' and 5'-TCAC-3' recognized in palindromic lac operator are the same as in lambda operator but their order is inverted form head to head to tail to tail. Different modes of aggregation of the monomers of the two proteins determine the different arrangements of the HTH motifs. Here we show that the HTH motif of lambda cro protein can replace the HTH motif of Lac repressor without changing its specificity. Such hybrid Lac repressor is unstable. It binds in vitro more weakly than Lac repressor but with the same specificity to ideal lac operator. It does not bind to consensus lambda operator. 相似文献
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M Hein C Madefessel B Haag K Teichmann A Post H J Galla 《Chemistry and physics of lipids》1992,63(3):223-233
The transepithelial resistance of confluent epithelial cell monolayers was monitored to investigate the influence of basic amino acids, Ca2+, protamine and protons on tight junction electrical resistance. In an accompanying paper we investigated the effect of these substances on the lamellar/hexagonal II phase transition in reconstituted phospholipid membranes containing phosphatidylserine and phosphatidylethanolamine. We conclude that the permeability of tight junctions may be described by a lipid phase equilibrium where the lamellar phase corresponds to an open state and the hexagonal lipid phase to the closed state of the cell contact. This dynamic lipid model is well suited to describe the morphological as well as functional properties of the tight junctions. 相似文献
5.
Loos Jacqueline Krauss Jochen Lyons Ashley Föst Stephanie Ohlendorf Constanze Racky Severin Röder Marina Hudel Lennart Herfert Volker Tscharntke Teja 《Biodiversity and Conservation》2021,30(8-9):2415-2432
Biodiversity and Conservation - Across Europe, calcareous grasslands become increasingly fragmented and their quality deteriorates through abandonment and land use intensification, both affecting... 相似文献
6.
Wolfgang Lorenz Constanze Buhrmann Ali Mobasheri Cora Lueders Mehdi Shakibaei 《Arthritis research & therapy》2013,15(5):R111
Introduction
We have previously reported that bacterial toxins, especially endotoxins such as lipopolysaccharides (LPS), might be important causative agents in the pathogenesis of rheumatoid arthritis (RA) in an in vitro model that simulates the potential effects of residing in damp buildings. Since numerous inflammatory processes are linked with the nuclear factor-κB (NF-κB), we investigated in detail the effects of LPS on the NF-κB pathway and the postulated formation of procollagen-endotoxin complexes.Methods
An in vitro model of human chondrocytes was used to investigate LPS-mediated inflammatory signaling.Results
Immunoelectron microscopy revealed that LPS physically interact with collagen type II in the extracellular matrix (ECM) and anti-collagen type II significantly reduced this interaction. BMS-345541 (a specific inhibitor of IκB kinase (IKK)) or wortmannin (a specific inhibitor of phosphatidylinositol 3-kinase (PI-3K)) inhibited the LPS-induced degradation of the ECM and apoptosis in chondrocytes. This effect was completely inhibited by combining BMS-345541 and wortmannin. Furthermore, BMS-345541 and/or wortmannin suppressed the LPS-induced upregulation of catabolic enzymes that mediate ECM degradation (matrix metalloproteinases-9, -13), cyclooxygenase-2 and apoptosis (activated caspase-3). These proteins are regulated by NF-κB, suggesting that the NF-κB and PI-3K pathways are involved in LPS-induced cartilage degradation. The induction of NF-κB correlated with activation of IκBα kinase, IκBα phosphorylation, IκBα degradation, p65 phosphorylation and p65 nuclear translocation. Further upstream, LPS induced the expression of Toll-like receptor 4 (TLR4) and bound with TLR4, indicating that LPS acts through TLR4.Conclusion
These results suggest that molecular associations between LPS/TLR4/collagen type II in chondrocytes upregulate the NF-κB and PI-3K signaling pathways and activate proinflammatory activity. 相似文献7.
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Gabrielle S. Prendergast Constanze M. Zurn A. Valeria Bers Ritchie M. Head Lars J. Hansson Jeremy C. Thomason 《Biofouling》2013,29(6):449-459
Many marine invertebrate larvae respond behaviourally to environmental settlement cues, yet behaviours are often only inferred from settlement patterns or are limited to laboratory studies. The behaviour of wild cypris larvae of Semibalanus balanoides L. was filmed on settlement tiles in the field. Tiles were of five different textures with a nested treatment of crude conspecific adult extract (AE). The effects of texture and AE on eleven defined behaviours were analysed. Texture affected the gross and net exploratory distances, velocity, acceleration and time spent exploring. AE attracted more cyprids during the first minute of immersion and increased the time spent on surfaces. Relatively few arrivals that either travel far and fast, or exit the surface rapidly, may indicate a lower chance of settlement. An increase in time spent on a surface may increase the probability of being in contact with the surface when the sign stimulus to settle occurs. 相似文献
10.
Constanze Hartmann Fabienne Mayenzet Jean-Paul Larcinese Olivier P. Haefliger Andrea Buettner Christian Starkenmann 《Steroids》2013,78(2):156-160
A method was developed for the quantification of 5-α-androst-16-en-3-one in human breast milk based on application of a stable isotope dilution assay using 5α-androst-16-en-3-one-6, 6-d2. The procedure includes extraction of the human milk by hexane with subsequent clean-up of the obtained extract by gel permeation and silica gel column chromatography. The extracted samples were analyzed by gas chromatography–mass spectrometry. Using this method 5-α-androst-16-en-3-one could be identified and for the first time quantified in a concentration range of 26–155 ng/kg in human milk. 相似文献