scholarly journals Molecular Architecture and Divalent Cation Activation of TvoK, a Prokaryotic Potassium Channel

2007 ◽  
Vol 282 (33) ◽  
pp. 24302-24309 ◽  
Author(s):  
Lyubov V. Parfenova ◽  
Karin Abarca-Heidemann ◽  
Brittany M. Crane ◽  
Brad S. Rothberg
Keyword(s):  
Potassium Channel ◽  
Divalent Cation ◽  
Molecular Architecture ◽  
Cation Activation

scholarly journals Divalent cation activation of galactosyltransferase in native mammary Golgi vesicles.

1990 ◽  
Vol 265 (26) ◽  
pp. 15731-15737 ◽  
Author(s):  
D.L. Witsell ◽  
C.E. Casey ◽  
M.C. Neville
Keyword(s):  
Divalent Cation ◽  
Golgi Vesicles ◽  
Cation Activation

scholarly journals Alterations in Receptor Activation and Divalent Cation Activation of Agonist Binding by Deletion of Intracellular Domains of the Glucagon Receptor

1997 ◽  
Vol 272 (12) ◽  
pp. 7765-7769 ◽  
Author(s):  
Gary G. Chicchi ◽  
Michael P. Graziano ◽  
Greg Koch ◽  
Patricia Hey ◽  
Kathleen Sullivan ◽  
...  
Keyword(s):  
Divalent Cation ◽  
Receptor Activation ◽  
Agonist Binding ◽  
Glucagon Receptor ◽  
Cation Activation ◽  
Intracellular Domains

The characterization of ATPases from the gill of the osteoglossid Osteoglossum bicirrhosum (aruaná)

1978 ◽  
Vol 56 (4) ◽  
pp. 795-800 ◽  
Author(s):  
Thomas W. Moon
Keyword(s):  
Ion Transport ◽  
Divalent Cation ◽  
Binding Sites ◽  
Microsomal Fraction ◽  
Specific Interaction ◽  
Cation Activation ◽  
Multiple Binding Sites ◽  
Monovalent Ions ◽  
Multiple Binding

Gill ATPases of the osteoglossid Osteoglossum bicirrhosum (aruaná) were isolated from the microsomal fraction (Nal pellet) and assayed in the presence of various cations and anions. The presence of Ca2+, Mg2+ (Mn2+), Na+ + K+ (with Mg2+) activated ATP hydrolyses; activation by Ca2+ and Mg2+ was similar and both were inhibited by thiocyanate, but the monovalent ions showed much lower activities. Activities in the presence of these ions were in the range reported for temperate teleosts such as the eel, goldfish, or trout. No HCO3− or NH4+ activation was detected. Apparent Km values for divalent cation activation were well above their respective environmental concentrations, but within the range reported for analogous enzymes of temperate teleosts. There is a specific interaction between Ca2+ and Mg2+ binding to the enzyme, but the results cannot distinguish between the existence of one enzyme with multiple binding sites, or a numberof ion-specific ATPases. These results suggest that the enzyme s assayed in this investigation are only indirectly, if at all, associated with gill ion transport in aruaná.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Exploration of cell wall architecture with the rapid-freeze deep-etch technique

1993 ◽  
Vol 51 ◽  
pp. 128-129
Author(s):  
Béatrice Satiat-Jeunemaitre ◽  
Chris Hawes
Keyword(s):  
Plant Cell ◽  
Cell Walls ◽  
Cell Biology ◽  
Molecular Model ◽  
Three Dimensional ◽  
Secretory Activity ◽  
Wall Structure ◽  
Specimen Preparation ◽  
Molecular Architecture ◽  
Plant Cell Walls

The comprehension of the molecular architecture of plant cell walls is one of the best examples in cell biology which illustrates how developments in microscopy have extended the frontiers of a topic. Indeed from the first electron microscope observation of cell walls it has become apparent that our understanding of wall structure has advanced hand in hand with improvements in the technology of specimen preparation for electron microscopy. Cell walls are sub-cellular compartments outside the peripheral plasma membrane, the construction of which depends on a complex cellular biosynthetic and secretory activity (1). They are composed of interwoven polymers, synthesised independently, which together perform a number of varied functions. Biochemical studies have provided us with much data on the varied molecular composition of plant cell walls. However, the detailed intermolecular relationships and the three dimensional arrangement of the polymers in situ remains a mystery. The difficulty in establishing a general molecular model for plant cell walls is also complicated by the vast diversity in wall composition among plant species.

Molecular architecture and functions of the neuronal cytoskeleton

1990 ◽  
Vol 48 (3) ◽  
pp. 2-3
Author(s):  
Nobutaka Hirokawa
Keyword(s):  
Major Elements ◽  
Molecular Structures ◽  
Organelle Transport ◽  
Molecular Architecture ◽  
Neuronal Morphogenesis ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
And Function ◽  
Small Clusters

In this symposium I will present our studies about the molecular architecture and function of the cytomatrix of the nerve cells. The nerve cell is a highly polarized cell composed of highly branched dendrites, cell body, and a single long axon along the direction of the impulse propagation. Each part of the neuron takes characteristic shapes for which the cytoskeleton provides the framework. The neuronal cytoskeletons play important roles on neuronal morphogenesis, organelle transport and the synaptic transmission. In the axon neurofilaments (NF) form dense arrays, while microtubules (MT) are arranged as small clusters among the NFs. On the other hand, MTs are distributed uniformly, whereas NFs tend to run solitarily or form small fascicles in the dendrites Quick freeze deep etch electron microscopy revealed various kinds of strands among MTs, NFs and membranous organelles (MO). These structures form major elements of the cytomatrix in the neuron. To investigate molecular nature and function of these filaments first we studied molecular structures of microtubule associated proteins (MAP1A, MAP1B, MAP2, MAP2C and tau), and microtubules reconstituted from MAPs and tubulin in vitro. These MAPs were all fibrous molecules with different length and formed arm like projections from the microtubule surface.

Projected Structure of the Surface Protein of Sulfolobus Spec. B12 Determined to a Resolution of 1.0 NM by Cryo-Electronmicroscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 102-103
Author(s):  
G. Lembcke ◽  
F. Zemlin
Keyword(s):  
Low Dose ◽  
Maximum Dose ◽  
Three Dimensional ◽  
Surface Protein ◽  
Protein S ◽  
Radiation Sensitivity ◽  
Specimen Preparation ◽  
Molecular Architecture ◽  
High Radiation ◽  
Fritz Haber

The thermoacidophilic archaebacterium Sulfolobus spec. B12 , which is closely related to Sulfolobus solfataricus , possesses a regularly arrayed surface protein (S-layer), which is linked to the plasma membrane via spacer elements spanning a distinct interspace of approximately 18 nm. The S-layer has p3-Symmetry and a lattice constant of 21 nm; three-dimensional reconstructions of negatively stained fragments yield a layer thickness of approximately 6-7 nm.For analysing the molecular architecture of Sulfolobus surface protein in greater detail we use aurothioglucose(ATG)-embedding for specimen preparation. Like glucose, ATG, is supposed to mimic the effect of water, but has the advantage of being less volatile. ATG has advantages over glucose when working with specimens composed exclusively of protein because of its higher density of 2.92 g cm-3. Because of its high radiation sensitivity electromicrographs has to be recorded under strict low-dose conditions. We have recorded electromicrographs with a liquid helium-cooled superconducting electron microscope (the socalled SULEIKA at the Fritz-Haber-lnstitut) with a specimen temperature of 4.5 K and with a maximum dose of 2000 e nm-2 avoiding any pre-irradiation of the specimen.

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