Immunoglobulin A (IgA) is the body’s the first line of defense against pathogens in the gut, like these two viruses (red). IgAs are a class of antibodies that can be dimers (background, bottom), tetramers (background, top), or even pentamers (front and center).
Cover art submission based on: Kumar N, Arthur CP, Ciferri C, Matsumoto ML. Structure of the secretory immunoglobulin A core. Science (80- ). 2020 Feb 28;367(6481):1008–14.
Structures: PDBs 6UE7, 6UE8, 6UEA