scholarly journals Three-dimensional EM structure of the ectodomain of integrin αVβ3 in a complex with fibronectin

2005 ◽  
Vol 168 (7) ◽  
pp. 1109-1118 ◽  
Author(s):  
Brian D. Adair ◽  
Jian-Ping Xiong ◽  
Catherine Maddock ◽  
Simon L. Goodman ◽  
M. Amin Arnaout ◽  
...  
Keyword(s):  
Particle Image ◽  
Three Dimensional ◽  
Integrin Αvβ3 ◽  
Dimensional Structure ◽  
Soluble Complex ◽  
Surface Receptors ◽  
Difference Map ◽  
Transmission Electron ◽  
Ligand Free ◽  
Site Binding

Integrins are αβ heterodimeric cell surface receptors that mediate transmembrane signaling by binding extracellular and cytoplasmic ligands. The ectodomain of integrin αVβ3 crystallizes in a bent, genuflexed conformation considered to be inactive (unable to bind physiological ligands in solution) unless it is fully extended by activating stimuli. We generated a stable, soluble complex of the Mn2+-bound αVβ3 ectodomain with a fragment of fibronectin (FN) containing type III domains 7 to 10 and the EDB domain (FN7-EDB-10). Transmission electron microscopy and single particle image analysis were used to determine the three-dimensional structure of this complex. Most αVβ3 particles, whether unliganded or FN-bound, displayed compact, triangular shapes. A difference map comparing ligand-free and FN-bound αVβ3 revealed density that could accommodate the RGD-containing FN10 in proximity to the ligand-binding site of β3, with FN9 just adjacent to the synergy site binding region of αV. We conclude that the ectodomain of αVβ3 manifests a bent conformation that is capable of stably binding a physiological ligand in solution.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Three Dimensional Structure of UMo8O26: Ordering of U-Vacancies

2002 ◽  
Vol 718 ◽  
Author(s):  
N.D. Zakharov ◽  
P. Werner
Keyword(s):  
Low Temperatures ◽  
Driving Force ◽  
Three Dimensional ◽  
Solid State Reaction Method ◽  
Dimensional Structure ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Edx Microanalysis

AbstractThe structure and composition of UMo8O26 synthesized by solid state reaction method have been investigated by High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction, and EDX microanalysis. The ordering of U vacancies results in considerable enlargement of unit cell parameters: an=6.44 nm, bn=1.45 nm, cn=1.6 nm. It is build up of four layers piled up in c direction. Each following layer is shifted relative to previous one by vector bn/4. Eight hexagonal tunnels in each layer are filled by U atoms, while the eight others are vacant (V). Interaction between U cations and vacancies is driving force for ordering. The variation of stoichiometry can be a reason for appearance of incommensurate modulations in these crystals. It seems plausible that this structure might also exhibit superconductivity at low temperatures.

Microfluidic Synthesis of Lipid-Polymer Hybrid Nanoparticles for Targeted Drug Delivery

MRS Advances ◽  
2016 ◽  
Vol 1 (29) ◽  
pp. 2155-2160
Author(s):  
Eri A. Takami ◽  
Folarin Erogbogbo
Keyword(s):  
Drug Delivery ◽  
Low Cost ◽  
Three Dimensional ◽  
Hybrid Nanoparticles ◽  
Dimensional Structure ◽  
Force Microscopy ◽  
Polymer Hybrid ◽  
Medical Issues ◽  
Transmission Electron ◽  
Size And Morphology

ABSTRACTLipid-polymer hybrid nanoparticles (LPHN) have great potential as drug delivery devices for treatment of serious medical issues such as cardiovascular disease, tuberculosis, and cancer. Nanoprecipitation is a commonly used method to synthesize LPHN in a low cost manner. However, this multi-step process proves to be difficult in consistently producing uniformly sized nanoparticles. Here we developed a microfluidic device that utilizes a three-channel pathway and mixer channel to synthesize uniformly sized LPHN in a controlled manner. Dynamic light scattering results of the microfluidic synthesized nanoparticles show decrease in diameter size from 140 nm to 40 nm as the Reynolds number of the channel inflow increases. Transmission electron microscopy confirms the size and morphology of the nanoparticles. Three dimensional structure of the LPHN were observed using atomic force microscopy. The production of higher quality nanoparticles using our microfluidics device can expedite the research and development process of drug delivering lipid polymer nanoparticles.

Unliganded GroEL at 2.8 Å: structure and functional implications

1995 ◽  
Vol 348 (1323) ◽  
pp. 113-119 ◽  
Keyword(s):  
Three Dimensional ◽  
Binding Pocket ◽  
Dimensional Structure ◽  
Outer Diameter ◽  
Central Channel ◽  
Crystal Forms ◽  
Monoclinic Form ◽  
C Terminus ◽  
Ligand Free ◽  
Dyad Symmetry

The three-dimensional structure of the E. coli chaperonin, GroEL, has been determined crystallo-graphically and refined to 2.7 Å in two crystal forms: an orthorhombic form from high salt and a monoclinic form from polyethylene glycol. The former is ligand free, the latter is both liganded with ATP analogues and ligand free. These structures provide a structural scaffold upon which to interpret extensive mutagenesis and biochemical studies. GroEL contains two sevenfold rotationally symmetric rings of identical 547-amino acid subunits. The rings are arranged ‘back-to-back’ with exact dyad symmetry to form a stubby cylinder that is 146 Å high with an outer diameter of about 143 Å. The cylinder has a substantial central channel that is unobstructed for the entire length of the cylinder and has a diameter of about 45 Å except for large bulges that lead into a sevenfold symmetric array of elliptical side windows in each ring. Each subunit is composed of three distinct domains: (i) an ‘equatorial’ domain that contains the N- and C-terminus and the ATP-binding pocket, .(ii) an ‘apical domain’ that forms the opening of the central channel and contains poorly ordered segments that mutational studies implicate in binding unfolded polypeptides and GroES, and (iii) an intermediate domain tht connects the other two domains and may serve to transmit allosteric adjustments.

Three-dimensional structure of a polymer/clay nanocomposite characterized by transmission electron microtomography

2006 ◽  
Vol 13 (7) ◽  
pp. 589-603 ◽  
Author(s):  
Hideo Nishioka ◽  
Ken-Ichi Niihara ◽  
Takeshi Kaneko ◽  
Junpei Yamanaka ◽  
Takashi Inoue ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Polymer Clay Nanocomposite ◽  
Transmission Electron

Preparation and Properties of Nanocomposite Hydrogel by Photoinitiated Polymerization

2013 ◽  
Vol 745-746 ◽  
pp. 499-506
Author(s):  
Meng Ge Xia ◽  
Sheng Liu ◽  
Yi Heng Wang ◽  
Yan Zhang ◽  
Yong Tao Wu ◽  
...  
Keyword(s):  
In Situ Polymerization ◽  
Three Dimensional ◽  
Soft Materials ◽  
Polymerization Process ◽  
Dimensional Structure ◽  
Hybrid Hydrogel ◽  
Illumination Time ◽  
Photoinitiated Polymerization ◽  
Transmission Electron ◽  
Nanoparticles Concentration

A novel hybrid hydrogel (SAT gel) based on covalent crosslinking was prepared by photoinitiated polymerization. Photoactive polystyrene (PS) nanoparticles were successfully synthesized by grafting photoinitiator 2-[p-(2-hydroxy-2-methylpropiophenone)] ethylene glycol methacrylate (HMEM) onto the surface of PS nanoparticles, and characterized by nuclear magnetic resonance (NMR), fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscope (HRTEM) and dynamic light scattering (DLS). In the presence of monomer (AAm), PS nanoparticles acting as multifunctional cross-linking agents, and in-situ polymerization was carried out on the surface of photoactive particles. This study focused on the effect of photoactive PS nanoparticles concentration and illumination time on the morphology and swelling behavior of SAT hydrogels. It revealed that the three-dimensional structure and swelling ratio decreased with the increasing concentration of PS nanoparticles. Moreover, the pore size compressed with extending the illumination time. Embedding photoactive nanoparticles into hydrogels network to prepare novel hydrogels had advantages of controllable polymerization process and short forming time. This method provided a new way to prepare soft materials and to design the intelligent hydrogels.

Three-Dimensional Structure of a Nanocomposite Material Consisting of Two Kinds of Nanofillers and Rubbery Matrix Studied by Transmission Electron Microtomography

2007 ◽  
Vol 40 (18) ◽  
pp. 6758-6764 ◽  
Author(s):  
Hiroshi Jinnai ◽  
Yuki Shinbori ◽  
Tatsuro Kitaoka ◽  
Keizo Akutagawa ◽  
Naruhiko Mashita ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Nanocomposite Material ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Transmission Electron
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