Tetramer

A tetramer is something formed out of four sub-units. The associated propriety is called tetramery.

In chemistry, the term refers to a molecule made of four monomers (for example kobophenol A, a molecule formed from four stilbenoids monomers).

In biochemistry, it similarly refers to a biomolecule formed of four units, that are the same (homotetramer), i.e. as in Concanavalin A or different (heterotetramer), i.e. hemoglobin has 2 different but similar sub-unit while immunoglobulin IGs have 2 very different sub-units and IgMs have an additional small unit J (junction). The different sub-units may have each their own activity, such as binding biotin in avidin tetramer, or have a common biological property, such as allosteric binding of oxygen in hemoglobin.