Related Experiment Video
Updated: Aug 16, 2026

Structure of HIV-1 Capsid Assemblies by Cryo-electron Microscopy and Iterative Helical Real-space Reconstruction
Published on: August 9, 2011
Topological organization of Sindbis virus capsid protein in isolated nucleocapsids
Abstract:
Sindbis virus nucleocapsids were isolated from mature virions by a two-step purification method. Detergent-treated virions were sedimented in sucrose gradients and the nucleocapsid peaks chromatographed on RNase-free Sephadex G-200. The purified nucleocapsids displayed several morphologies when examined in the electron microscope. These morphologies, and the results of double-angle shadowing, suggest that the core of this enveloped virus has the shape of a regular icosahedron with a triangulation number of 4. Peptide mapping of capsid protein obtained from nucleocapsids that had been radioiodinated by a variety of means, indicated that of the four tyrosine residues in the protein, only Tyr180 was exposed at the surface of the icosahedral structure. The other three residues were not exposed on the outer surface of the nucleocapsid shell, nor on the surface of capsid protein itself, implying that they were buried within the folded protein.
Related Concept Videos
Viral Structure
Protein Complex Assembly
Many viruses self-assemble into a fully functional unit using the infected host cell to...
Introduction to Virus
Size and Structure of Viral Genomes
Subviral Agents
Inhibitors of Virion Maturation and Assembly

