{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"CD8 is a transmembrane glycoprotein that serves as a co-receptor for the T-cell receptor. Like the T-cell receptor, CD8 binds to a major histocompatibility complex molecule that is specific for the Class I major histocompatibility complex protein. To function, CD8 forms a dimer, consisting of a pair of CD8 chains. The most common form of CD8 is composed of a CD8-α and CD8-β chain, both members of the immunoglobulin superfamily with an immunoglobulin variable-like extracellular domain connected to the membrane by a thin stalk, and an intracellular tail."}]}]}