hexamerization

Hexamerization is the process by which six protein or peptide subunits come together to form a hexamer, a particular type of oligomer. The six subunits can be identical (homohexamer) or different (heterohexamer). Hexamers may arrange as a circular ring with sixfold symmetry or as more complex structures such as two interfacing trimers, which can yield D3 symmetry. This organization often places catalytic or binding sites at subunit interfaces and can influence stability, cooperativity, and regulation of activity.

Hexameric assemblies occur in a range of biological contexts. In enzymes, the hexameric state can support allosteric regulation and substrate channeling across interfaces. In structural and signaling proteins, hexamers can provide a stable scaffold or create central pores. In virology, many icosahedral capsids incorporate hexameric capsomers into their shell, working together with pentameric units to achieve closed geometry.

Hexamerization can be driven by concentration, ionic strength, pH, ligand binding, or post-translational modifications, and is often reversible. Disassembly into smaller units can modulate function or signaling. Determining hexameric structure and assembly mechanisms relies on methods such as X-ray crystallography, cryo-electron microscopy, analytical ultracentrifugation, and cross-linking coupled with mass spectrometry.