Positions of mutations in the SARS-CoV-2 Omicron variant compared to the original strain, showing amino acid substitutions (yellow), deletions (red), and insertions (green). In this trimeric structure, two monomers (gray and light blue) have their receptor-binding domains in the "down" conformation while one (dark blue) is in the "up" or "open" conformation. "Side" view shows receptor-binding domains at the top of the image; the membrane would be located at the bottom. Mutation data source from WHO. Rendered from PDB: 6VYB​.

Structure, Function, and Antigenicity of the SARS-CoV-2 Spike Glycoprotein. Walls, A.C., Park, Y.J., Tortorici, M.A., Wall, A., McGuire, A.T., Veesler, D. (2020) Cell 181: 281