Characterization of actin, actinin, and myosin isolated from Physarum

1980 ◽  
Vol 58 (7) ◽  
pp. 750-759 ◽  
Author(s):  
Sadashi Hatano ◽  
Katsushi Owaribe ◽  
Fumio Matsumura ◽  
Takayuki Hasegawa ◽  
Sho Takahashi
Keyword(s):  
Physicochemical Properties ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Striated Muscle ◽  
Regulatory Protein ◽  
Motive Force ◽  
Protoplasmic Streaming ◽  
Similarities And Differences

Our work on actin and myosin from Physarum is briefly reviewed, and the physicochemical properties of these proteins are compared with those of the corresponding proteins obtained from rabbit striated muscle. In this article both similarities and differences between these preparations are emphasized in order to characterize the Physarum actomyosin system. Some properties of Physarum actinin, a regulatory protein of actin polymerization, are also reported. Finally, the assembly and disassembly of F-actin filaments in the reversible superprecipitation of Physarum actomyosin are demonstrated. The mechanism of generation of the motive force for protoplasmic streaming in plasmodium is discussed in the light of these findings.

scholarly journals Nebulin Interacts with CapZ and Regulates Thin Filament Architecture within the Z-Disc

2008 ◽  
Vol 19 (5) ◽  
pp. 1837-1847 ◽  
Author(s):  
Christopher T. Pappas ◽  
Nandini Bhattacharya ◽  
John A. Cooper ◽  
Carol C. Gregorio
Keyword(s):  
Actin Filaments ◽  
Thin Filament ◽  
Actin Polymerization ◽  
Striated Muscle ◽  
Solid Phase ◽  
Molecular Model ◽  
Direct Interaction ◽  
Tryptophan Fluorescence ◽  
Actin Binding

The barbed ends of actin filaments in striated muscle are anchored within the Z-disc and capped by CapZ; this protein blocks actin polymerization and depolymerization in vitro. The mature lengths of the thin filaments are likely specified by the giant “molecular ruler” nebulin, which spans the length of the thin filament. Here, we report that CapZ specifically interacts with the C terminus of nebulin (modules 160–164) in blot overlay, solid-phase binding, tryptophan fluorescence, and SPOTs membrane assays. Binding of nebulin modules 160–164 to CapZ does not affect the ability of CapZ to cap actin filaments in vitro, consistent with our observation that neither of the two C-terminal actin binding regions of CapZ is necessary for its interaction with nebulin. Knockdown of nebulin in chick skeletal myotubes using small interfering RNA results in a reduction of assembled CapZ, and, strikingly, a loss of the uniform alignment of the barbed ends of the actin filaments. These data suggest that nebulin restricts the position of thin filament barbed ends to the Z-disc via a direct interaction with CapZ. We propose a novel molecular model of Z-disc architecture in which nebulin interacts with CapZ from a thin filament of an adjacent sarcomere, thus providing a structural link between sarcomeres.

scholarly journals Characterization of Human Palladin, a Microfilament-associated Protein

2001 ◽  
Vol 12 (10) ◽  
pp. 3060-3073 ◽  
Author(s):  
Olli-Matti Mykkänen ◽  
Mikaela Grönholm ◽  
Mikko Rönty ◽  
Maciej Lalowski ◽  
Paula Salmikangas ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Actin Filaments ◽  
Striated Muscle ◽  
Periodic Structures ◽  
Control Cell ◽  
Cytoskeletal Proteins ◽  
Hybrid Search ◽  
Morphological Alterations ◽  
Nonmuscle Cells

Actin-containing microfilaments control cell shape, adhesion, and contraction. In striated muscle, α-actinin and other Z-disk proteins coordinate the organization and functions of actin filaments. In smooth muscle and nonmuscle cells, periodic structures termed dense bodies and dense regions, respectively, are thought to serve functions analogous to Z-discs. We describe here identification and characterization of human palladin, a protein expressed mainly in smooth muscle and nonmuscle and distributed along microfilaments in a periodic manner consistent with dense regions/bodies. Palladin contains three Ig-domains most homologous to the sarcomeric Z-disk protein myotilin. The N terminus includes an FPPPP motif recognized by the Ena-Vasp homology domain 1 domain in Ena/vasodilatator-stimulated phosphoprotein (VASP)/Wiscott-Aldrich syndrome protein (WASP) protein family. Cytoskeletal proteins with FPPPP motif target Ena/VASP/WASP proteins to sites of actin modulation. We identified palladin in a yeast two-hybrid search as an ezrin-associated protein. An interaction between palladin and ezrin was further verified by affinity precipitation and blot overlay assays. The interaction was mediated by the α-helical domain of ezrin and by Ig-domains 2–3 of palladin. Ezrin is typically a component of the cortical cytoskeleton, but in smooth muscle cells it is localized along microfilaments. These cells express palladin abundantly and thus palladin may be involved in the microfilament localization of ezrin. Palladin expression was up-regulated in differentiating dendritic cells (DCs), coinciding with major cytoskeletal and morphological alterations. In immature DCs, palladin localized in actin-containing podosomes and in mature DCs along actin filaments. The regulated expression and localization suggest a role for palladin in the assembly of DC cytoskeleton.

High-Resolution Measurements of Subsarcomere Calcium-Binding Distributions from EPXMA Images

1996 ◽  
Vol 54 ◽  
pp. 292-293
Author(s):  
M. E. Cantino ◽  
J. G. Eichen
Keyword(s):  
Calcium Binding ◽  
Thin Filament ◽  
Direct Evidence ◽  
Striated Muscle ◽  
Regulatory Protein ◽  
Psoas Muscle ◽  
Thin Filaments ◽  
Regulation Of Contraction

The distribution of calcium binding to thin filaments in vertebrate striated muscle provides clues about the role of calcium in regulation of contraction. A number of studies have suggested that the extent of Ca binding to the thin filament regulatory protein, troponin, is enhanced by the attachment of crossbridges. Electron probe X-ray microanalysis (EPXMA) has provided direct evidence of this enhancement by showing that more Ca is found in the overlap than in the nonoverlap region of sarcomeres in skinned rabbit psoas muscle in rigor. In that study, characterization of the spatial extent of this enhancement was limited by the pixel width of bands (4 pixels) within which Ca counts were averaged at each position across the sarcomere. In order to improve the resolution with which data are extracted from the image we have developed an automated routine for averaging calcium counts from successive columns of pixels across each half sarcomere in the image.

Orientation of actin filaments during motion in motility assay

1995 ◽  
Vol 53 ◽  
pp. 52-53
Author(s):  
J. Borejdo ◽  
S. Burlacu
Keyword(s):  
Actin Filaments ◽  
Thin Filament ◽  
Striated Muscle ◽  
Myosin Head ◽  
Classical Method ◽  
Polarization Of Fluorescence ◽  
Single Protein ◽  
Intracellular Organelles ◽  
Change Orientation ◽  
Active Entity

Polarization of fluorescence is a classical method to assess orientation or mobility of macromolecules. It has been a common practice to measure polarization of fluorescence through a microscope to characterize orientation or mobility of intracellular organelles, for example anisotropic bands in striated muscle. Recently, we have extended this technique to characterize single protein molecules. The scientific question concerned the current problem in muscle motility: whether myosin heads or actin filaments change orientation during contraction. The classical view is that the force-generating step in muscle is caused by change in orientation of myosin head (subfragment-1 or SI) relative to the axis of thin filament. The molecular impeller which causes this change resides at the interface between actin and SI, but it is not clear whether only the myosin head or both SI and actin change orientation during contraction. Most studies assume that observed orientational change in myosin head is a reflection of the fact that myosin is an active entity and actin serves merely as a passive "rail" on which myosin moves.

Synthesis, Characterization, and Dynamic Behavior of Well-defined Dithiomaleimide-functionalized Maltodextrins

2020 ◽  
Vol 17 (2) ◽  
pp. 85-89
Author(s):  
Francisco J. Hidalgo ◽  
Nathan A.P. Lorentz ◽  
TinTin B. Luu ◽  
Jonathan D. Tran ◽  
Praveen D. Wickremasinghe ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Dynamic Behavior ◽  
Industrial Applications ◽  
19F Nmr ◽  
Nmr Studies ◽  
Synthetic Pathway ◽  
End Groups ◽  
Sugar End

: Maltodextrins have an increasing number of biomedical and industrial applications due to their attractive physicochemical properties such as biodegradability and biocompatibility. Herein, we describe the development of a synthetic pathway and characterization of thiol-responsive maltodextrin conjugates with dithiomaleimide linkages. 19F NMR studies were also conducted to demonstrate the exchange dynamics of the dithiomaleimide-functionalized sugar end groups.

Chemical characterization of tequila maturation process and their connection with the physicochemical properties of the cask

2021 ◽  
Vol 98 ◽  
pp. 103804
Author(s):  
Walter M. Warren-Vega ◽  
Rocío Fonseca-Aguiñaga ◽  
Linda V. González-Gutiérrez ◽  
Francisco Carrasco-Marín ◽  
Ana I. Zárate-Guzmán ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Chemical Characterization ◽  
Maturation Process

scholarly journals Physicochemical Characterization Cascade of Nanoadjuvant–Antigen Systems for Improving Vaccines

Vaccines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 544
Author(s):  
Giuditta Guerrini ◽  
Antonio Vivi ◽  
Sabrina Gioria ◽  
Jessica Ponti ◽  
Davide Magrì ◽  
...  
Keyword(s):  
Immune Response ◽  
Protein Structure ◽  
Physicochemical Properties ◽  
Physicochemical Characterization ◽  
Protein Antigen ◽  
Efficacy And Safety

Adjuvants have been used for decades to enhance the immune response to vaccines, in particular for the subunit-based adjuvants. Physicochemical properties of the adjuvant-protein antigen complexes, such as size, morphology, protein structure and binding, influence the overall efficacy and safety of the vaccine. Here we show how to perform an accurate physicochemical characterization of the nanoaluminum–ovalbumin complex. Using a combination of existing techniques, we developed a multi-staged characterization strategy based on measurements of increased complexity. This characterization cascade has the advantage of being very flexible and easily adaptable to any adjuvant-protein antigen combinations. It will contribute to control the quality of antigen–adjuvant complexes and immunological outcomes, ultimately leading to improved vaccines.

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