Three-dimensional reconstruction of a complex of human alpha 2-macroglobulin with monomaleimido Nanogold (Au1.4nm) embedded in ice.

@article{Boisset1992ThreedimensionalRO,
  title={Three-dimensional reconstruction of a complex of human alpha 2-macroglobulin with monomaleimido Nanogold (Au1.4nm) embedded in ice.},
  author={Nicolas Boisset and Robert A. Grassucci and Pawel A. Penczek and Etienne Delain and François Pochon and Joachim Frank and Josette Lamy},
  journal={Journal of structural biology},
  year={1992},
  volume={109 1},
  pages={
          39-45
        }
}
Cysteine 949 and glutamine 952 are known to be part of the thiol ester site of each of the four subunits of human alpha 2-macroglobulin (alpha 2M). The hydrolysis of this thiol ester bound to methylamine results in the incorporation of the amine and liberation of a free sulfhydryl group that can be specifically labeled. Therefore, a high-resolution marker specific for the sulfhydryl groups, the monomaleimido Nanogold (Au1.4nm) cluster was used to bind this amino acid. After cryoelectron… Expand
Three‐Dimensional Reconstruction of Human α2‐Macroglobulin and Refinement of the Localization of Thiol Ester Bonds with Monomaleimido Nanogold a
TLDR
Human alpha-2-macroglobulin is a 720-kDa macromolecular protease scavenger that can be induced by methylamine in a process where the thiol ester bonds are hydrolyzed without initial alteration of the bait. Expand
Three-dimensional structures of the human alpha 2-macroglobulin-methylamine and chymotrypsin complexes.
TLDR
The three-dimensional structures of chymotrypsin- and methylamine-treated negatively stained human alpha 2-macroglobulin have been determined by weighted back projection from electron microscope data by finding that the H-shaped front projection of the molecule is related to the smaller ellipsoidal end view by a rotation of 90 degrees about the crossbar of the H. Expand
Low Resolution X-ray Structure of Human Methylamine-treated α2-Macroglobulin (*)
The structure of methylamine-treated human α2-macroglobulin (α2M-MA), a 720-kDa tetrameric inactivated proteinase inhibitor from plasma, has been determined to a resolution of 10 Å. Data wereExpand
Structure‐Function Relationships of Human α2‐Macroglobulin
TLDR
The authors' studies indicate that the thioester linkages serve to maintain the native molecule in a strained, twisted configuration and their cleavage upon reaction with the proteinase initiates the change in the structure of a2M that results in its entrapment. Expand
Similar Architectures of Native and Transformed Human α2-Macroglobulin Suggest the Transformation Mechanism*
TLDR
These structures suggest that α2M conformational change involves a strong lateral compression and a vertical stretching of the native particle seen in its four-petaled flower view to produce the H view of the transformed form. Expand
Symmetry in the 2.25 MDa homomultimeric phosphoenolpyruvate synthase fromStaphylothermus marinus: Analyses of negatively stained preparations
TLDR
Computerised image analysis and reconstruction from untilted and tilted stained preparations are used to show that the major axes of rotational symmetry inherent in projections of the structure are 3-fold and potentially 2-fold, and the archaeal complex probably has an octahedral architecture which has the same point group symmetry as the cube. Expand
Nanogold as a Specific Marker for Electron Cryotomography
TLDR
These results demonstrate that the 1.4 nm Nanogold cluster is visible in tomograms of typically thick samples (∼250 nm) recorded with defocuses appropriate for large macromolecules and is thus an effective marker. Expand
Gold-tagged RNA-A probe for macromolecular assemblies.
TLDR
This study demonstrates the potential use of nucleic acids that are covalently labeled with gold clusters for the structural characterization of protein-RNA complexes. Expand
Gold nanoparticle-protein arrays improve resolution for cryo-electron microscopy.
TLDR
A labeling method to prepare protein 2D arrays using gold nanoparticles (NPs) interconnecting genetic tag sites on proteins using 3.9-nm Au NPs functionalized with nickel-nitrilotriacetic acid is presented. Expand
Differential distribution of lumican and fibromodulin in tooth cementum.
The objectives of this study were to isolate and characterize the major proteoglycans of tooth cementum in relation to the tissue's mineralization. Cementum was collected from the root apex region ofExpand
...
1
2
...

References

SHOWING 1-10 OF 28 REFERENCES
Separation and localization of the four cysteine-949 residues in human alpha 2-macroglobulin using fluorescence energy transfer.
TLDR
These separations, small in the context of the alpha 2-macroglobulin tetramer, severely restrict the possible locations of the four Cys949 residues. Expand
Electron microscopical localization of the alpha 2-macroglobulin thiol ester sites.
TLDR
It is concluded that the thiol esters responsible for the covalent attachment of the proteinases (and other molecules) may be located more in the distal parts of thealpha 2M molecules, while the proteinase molecules are finally trapped near to the centre of the alpha 2M molecule. Expand
Localization of the proteinases in the human alpha 2-macroglobulin-chymotrypsin complex by image processing of electron micrographs.
TLDR
The comparison of the alpha 2M molecules transformed either by immobilized chymotrypsin or methylamine shows that the proteolysis of the bait regions seems of minimal importance for the general shape of the molecule and provides a direct visualization of the actual role of the thiol esters in the conformational change. Expand
Further characterization of the covalent linking reaction of alpha 2-macroglobulin.
TLDR
It is proposed that the site for incorporation of methylamine in each subunit is a thiol ester, which in S-alpha 2M (the electrophoretically "slow" form) is sterically shielded from reaction with large nucleophiles, but is revealed as a highly reactive group, free from steric hindrance, after the proteolytic cleavage. Expand
The molecular organization of human alpha 2-macroglobulin. An immunoelectron microscopic study with monoclonal antibodies.
TLDR
New models for the three-dimensional organization of native and chymotrypsin-transformed dimeric and tetrameric human alpha 2M are proposed. Expand
Electron microscope studies of human alpha 2-macroglobulin-chymotrypsin complex: demonstration that the two structures assigned to native and proteolyzed alpha 2-macroglobulin represent two views of the proteolyzed molecule.
Electron microscope studies of native and protease-bound human alpha 2-macroglobulin have led to two contradictory models for these two structures. One viewpoint maintains that the native structureExpand
Image analysis and three‐dimensional model of chymotrypsin‐transformed human alpha2‐macroglobulin complexed with a monoclonal antibody specific for this conformation
TLDR
An ultrastructural study of the binding of a monoclonal antibody specific for this conformation of α2M, which appears asymmetrical, presents 2 conformational states (which the authors describe as relaxed and twisted), and has flexible arms. Expand
The structure of alpha 2-macroglobulin-methylamine after papain digestion as determined by electron microscopy.
TLDR
Since the alpha 2M receptor-binding sites are removed by papain digestion, the studies presented here support the location of the receptor- binding sites near the apices of the lateral walls. Expand
Structure of native alpha 2-macroglobulin and its transformation to the protease bound form.
TLDR
It is proposed that the proteolyzed form of alpha 2-macroglobulin is functionally asymmetric in that both protease binding sites reside on the same half of the complex. Expand
A thiol‐ester in α2‐macroglobulin cleaved during proteinase complex formation
The glycoprotein crs-macroglobulin ((YAM), M, 725 000, is unique among plasma proteins in being able to form complexes with proteinases from all 4 classes (EC 3.4 2 1-24) [ l-31. The function of olMExpand
...
1
2
3
...