Related Experiment Video
Updated: Jul 11, 2026

Generation of Native, Untagged Huntingtin Exon1 Monomer and Fibrils Using a SUMO Fusion Strategy
Published on: June 27, 2018
Intra- and intermolecular beta-pleated sheet formation in glutamine-repeat inserted myoglobin as a model for
M Tanaka1, I Morishima, T Akagi
1Laboratory for CAG repeat diseases, RIKEN Brain Science Institute, Saitama 351-0198, Japan.
Abstract:
An aberrant structure of the expanded polyglutamine might be involved in the formation of aggregates in CAG repeat diseases. To elucidate structural properties of the expanded polyglutamine, we prepared sperm whale myoglobin (Mb) mutants, in which 12, 28, 35, and 50 repeats of glutamine were inserted at the corner between the C and D helices (Gln(12), Gln(28), Gln(35), and Gln(50), respectively). Circular dichroism and IR spectroscopies showed that the expanded polyglutamine, which was recognized by the monoclonal antibody 1C2 in Gln(28), Gln(35), and Gln(50) Mb forms an antiparallel beta-pleated sheet structure. Gln(50) Mb aggregates were found to comprise an intermolecular antiparallel beta-pleated sheet. Fluorescence together with (1)H NMR spectra revealed partial unfolding of the protein surface in Gln(35) and Gln(50) Mb, although the structural changes in the protein core were rather small. The present results indicate that the fluctuating beta-pleated sheet of the expanded polyglutamine exposed on the protein surface facilitates the formation of aggregates through intermolecular interactions. The present study has first established and characterized structural properties of a molecular model for polyglutamine diseases in which various lengths of polyglutamine including a pathologically expanded glutamine repeat were inserted into a structurally known protein.
Related Concept Videos
Protein Organization
Protein Folding
Amyloid Fibrils
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
Protein Organization
The primary structure of a protein is its amino acid sequence.
Protein Folding
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Amyloid Fibrils
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...

