Tetramere

Tetramere is a term used in biochemistry and related fields to designate a molecular assembly composed of four subunits. It is most commonly applied to four-protein assemblies (quaternary structure), but the word also appears in polymer and supramolecular contexts as a four-unit motif. In some texts, tetramere is used interchangeably with the more standard term tetramer.

Tetrameres can be classified as homo-tetrameres, where all subunits are identical, or hetero-tetrameres, containing different subunits. Subunits may be held together by non-covalent interactions such as hydrogen bonding, ionic interactions, and hydrophobic effects, or by covalent bonds in engineered constructs. The arrangement of subunits often gives rise to symmetry and cooperative behavior among units.

Biology provides several well-characterized tetrameres. Hemoglobin is a classic example, a heterotetramer of two alpha and two beta subunits that enables cooperative oxygen binding. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a common homotetramer in many organisms. Some transcription factors, including p53, also form tetramers to achieve specific DNA-binding functions. Tetramerization can influence stability, regulatory properties, and catalytic efficiency, and it often enables allosteric effects or coordinated activity among subunits.

In chemistry and materials science, tetrameres serve as building blocks for self-assembled networks and four-unit motifs in polymer design and nanostructures. Terminology varies by field, and tetramere remains less common than tetramer in many contexts.