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  • Models, Molecular  (3)
  • 78.65.Ez  (1)
  • 1
    Publikationsdatum: 2014-12-04
    Beschreibung: Muscle contraction is initiated by the release of calcium (Ca(2+)) from the sarcoplasmic reticulum into the cytoplasm of myocytes through ryanodine receptors (RyRs). RyRs are homotetrameric channels with a molecular mass of more than 2.2 megadaltons that are regulated by several factors, including ions, small molecules and proteins. Numerous mutations in RyRs have been associated with human diseases. The molecular mechanism underlying the complex regulation of RyRs is poorly understood. Using electron cryomicroscopy, here we determine the architecture of rabbit RyR1 at a resolution of 6.1 A. We show that the cytoplasmic moiety of RyR1 contains two large alpha-solenoid domains and several smaller domains, with folds suggestive of participation in protein-protein interactions. The transmembrane domain represents a chimaera of voltage-gated sodium and pH-activated ion channels. We identify the calcium-binding EF-hand domain and show that it functions as a conformational switch allosterically gating the channel.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Efremov, Rouslan G -- Leitner, Alexander -- Aebersold, Ruedi -- Raunser, Stefan -- England -- Nature. 2015 Jan 1;517(7532):39-43. doi: 10.1038/nature13916. Epub 2014 Dec 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany [2] Structural Biology Research Center, Vlaams Instituut voor Biotechnologie (VIB), 1050 Brussels, Belgium [3] Structural Biology Brussels, Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium. ; Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland. ; 1] Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland [2] Faculty of Science, University of Zurich, 8057 Zurich, Switzerland. ; Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25470059" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Allosteric Regulation/drug effects ; Animals ; Calcium/deficiency/metabolism/pharmacology ; Cryoelectron Microscopy ; Cytoplasm/metabolism ; Hydrogen-Ion Concentration ; Inositol 1,4,5-Trisphosphate Receptors/chemistry ; Ion Channel Gating/drug effects ; Models, Molecular ; Protein Binding ; Protein Structure, Tertiary/drug effects ; Rabbits ; Ryanodine Receptor Calcium Release Channel/chemistry/*metabolism/*ultrastructure ; Tacrolimus Binding Protein 1A/chemistry/metabolism/ultrastructure
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2014-10-02
    Beschreibung: Mitochondrial ribosomes (mitoribosomes) are extensively modified ribosomes of bacterial descent specialized for the synthesis and insertion of membrane proteins that are critical for energy conversion and ATP production inside mitochondria. Mammalian mitoribosomes, which comprise 39S and 28S subunits, have diverged markedly from the bacterial ribosomes from which they are derived, rendering them unique compared to bacterial, eukaryotic cytosolic and fungal mitochondrial ribosomes. We have previously determined at 4.9 A resolution the architecture of the porcine (Sus scrofa) 39S subunit, which is highly homologous to the human mitoribosomal large subunit. Here we present the complete atomic structure of the porcine 39S large mitoribosomal subunit determined in the context of a stalled translating mitoribosome at 3.4 A resolution by cryo-electron microscopy and chemical crosslinking/mass spectrometry. The structure reveals the locations and the detailed folds of 50 mitoribosomal proteins, shows the highly conserved mitoribosomal peptidyl transferase active site in complex with its substrate transfer RNAs, and defines the path of the nascent chain in mammalian mitoribosomes along their idiosyncratic exit tunnel. Furthermore, we present evidence that a mitochondrial tRNA has become an integral component of the central protuberance of the 39S subunit where it architecturally substitutes for the absence of the 5S ribosomal RNA, a ubiquitous component of all cytoplasmic ribosomes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Greber, Basil J -- Boehringer, Daniel -- Leibundgut, Marc -- Bieri, Philipp -- Leitner, Alexander -- Schmitz, Nikolaus -- Aebersold, Ruedi -- Ban, Nenad -- England -- Nature. 2014 Nov 13;515(7526):283-6. doi: 10.1038/nature13895. Epub 2014 Sep 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH Zurich, CH-8093 Zurich, Switzerland. ; Department of Biology, Institute of Molecular Systems Biology, Auguste-Piccard-Hof 1, ETH Zurich, CH-8093 Zurich, Switzerland. ; 1] Department of Biology, Institute of Molecular Systems Biology, Auguste-Piccard-Hof 1, ETH Zurich, CH-8093 Zurich, Switzerland [2] Faculty of Science, University of Zurich, CH-8057 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25271403" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Cross-Linking Reagents ; Cryoelectron Microscopy ; Mass Spectrometry ; Mitochondria/*chemistry/ultrastructure ; Mitochondrial Proteins/*chemistry/metabolism/*ultrastructure ; Models, Molecular ; Molecular Conformation ; Peptidyl Transferases/metabolism ; RNA, Ribosomal/chemistry/metabolism/ultrastructure ; Ribosome Subunits, Large/*chemistry/genetics/*ultrastructure ; Sus scrofa/genetics
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Publikationsdatum: 2013-12-24
    Beschreibung: Mitochondrial ribosomes synthesize a number of highly hydrophobic proteins encoded on the genome of mitochondria, the organelles in eukaryotic cells that are responsible for energy conversion by oxidative phosphorylation. The ribosomes in mammalian mitochondria have undergone massive structural changes throughout their evolution, including ribosomal RNA shortening and acquisition of mitochondria-specific ribosomal proteins. Here we present the three-dimensional structure of the 39S large subunit of the porcine mitochondrial ribosome determined by cryo-electron microscopy at 4.9 A resolution. The structure, combined with data from chemical crosslinking and mass spectrometry experiments, reveals the unique features of the 39S subunit at near-atomic resolution and provides detailed insight into the architecture of the polypeptide exit site. This region of the mitochondrial ribosome has been considerably remodelled compared to its bacterial counterpart, providing a specialized platform for the synthesis and membrane insertion of the highly hydrophobic protein components of the respiratory chain.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Greber, Basil J -- Boehringer, Daniel -- Leitner, Alexander -- Bieri, Philipp -- Voigts-Hoffmann, Felix -- Erzberger, Jan P -- Leibundgut, Marc -- Aebersold, Ruedi -- Ban, Nenad -- England -- Nature. 2014 Jan 23;505(7484):515-9. doi: 10.1038/nature12890. Epub 2013 Dec 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Biology, Institute of Molecular Biology and Biophysics, Schafmattstrasse 20, ETH Zurich, CH-8093 Zurich, Switzerland [2]. ; Department of Biology, Institute of Molecular Systems Biology, Wolfgang-Pauli-Strasse 16, ETH Zurich, CH-8093 Zurich, Switzerland. ; Department of Biology, Institute of Molecular Biology and Biophysics, Schafmattstrasse 20, ETH Zurich, CH-8093 Zurich, Switzerland. ; 1] Department of Biology, Institute of Molecular Systems Biology, Wolfgang-Pauli-Strasse 16, ETH Zurich, CH-8093 Zurich, Switzerland [2] Faculty of Science, University of Zurich, CH-8057 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24362565" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Cattle ; Cryoelectron Microscopy ; Hydrophobic and Hydrophilic Interactions ; Mass Spectrometry ; Mitochondria/*chemistry/ultrastructure ; Mitochondrial Proteins/chemistry/ultrastructure ; Models, Molecular ; Nucleic Acid Conformation ; Protein Conformation ; RNA, Ribosomal, 16S/chemistry/ultrastructure ; Ribosomal Proteins/chemistry/ultrastructure ; Ribosome Subunits/*chemistry/ultrastructure ; Swine
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 60 (1995), S. 97-101 
    ISSN: 1432-0630
    Schlagwort(e): 78.65.Ez ; 42.65.Cq
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract In metal-island films consisting of nanometer particles on a transparent substrate irradiated light fields can be locally enhanced by electron-plasma resonances. Therefore, nonlinear optical processes should be enhanced dramatically. However, second-order nonlinear processes as second-harmonic generation occuring in the surface are strongly reduced by the centrosymmetric shape of the metal particles. It is found that this surface-specific contribution to second-harmonic generation is less enhanced, as is expected from the field enhancement. The “bulk” contribution, at smooth metal surfaces known to be much weaker than the contribution from the “real surface”, is strongly enhanced by the plasma resonances without symmetry restrictions and becomes comparably important.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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