homotetramero

Homotetramero, or homotetramer in English, refers to a protein complex composed of four identical polypeptide subunits that associate to form a single functional assembly. The four-fold arrangement commonly yields C4 symmetry, with each subunit contributing to the active-site architecture or to the overall stability of the complex.

As a type of quaternary structure, the homotetrameric assembly often positions four potential active sites around a central axis. Subunit interfaces drive cooperative interactions, and allostery can regulate activity by altering interface contacts or subunit conformation in response to ligands.

Formation and stability are governed by noncovalent interactions, including hydrophobic packing, hydrogen bonding, and electrostatic contacts. Tetramer assembly can be sensitive to pH and ionic strength; changes can promote dissociation into monomers or dimers. Some homotetramers are stabilized by ligands or cofactors, which can modulate activity or structural integrity.

Techniques used to study homotetramers include X-ray crystallography, cryo-electron microscopy, analytical ultracentrifugation, and size-exclusion chromatography with multi-angle light scattering. In English-language literature, homotetramer is standard; in some languages the term homotetramero appears. The broader term tetramer refers to any four-subunit complex, including heterotetramers, where subunits are not identical.