homomeric

Homomeric is a term used in biochemistry and molecular biology to describe a macromolecular complex formed entirely from identical subunits. In a homomer, all subunits are the same polypeptide or share identical folding domains, arranged in a symmetric stoichiometry. The opposite term is heteromeric, where a complex contains different subunits. The designation often implies a specific oligomeric state, such as a homodimer, homotrimer, or homotetramer, though the word itself does not specify the exact number of subunits.

Homomeric assemblies are common across enzymes, structural proteins, and membrane proteins. Examples include aquaporins, which form tetramers composed of identical subunits, and various bacterial channels that are believed to be homo-oligomeric. In contrast, many receptor and enzyme complexes are heteromeric, consisting of different subunits that contribute distinct interfaces and functional properties. Filamentous structures like actin polymers can also be described as homomeric in the sense that repeating identical subunits assemble into higher-order structures.

Functional and evolutionary implications accompany homomerism. Symmetric, identical subunits can facilitate cooperative interactions and allostery, influence stability and folding, and affect pharmacology or regulation. Evolutionarily, homomeric assemblies may reflect ancestral states or arise through gene duplication and subsequent divergence that leads to heteromeric interfaces.

Detection and characterization rely on structural and biochemical methods, including X-ray crystallography, cryo-electron microscopy, crosslinking, and mass spectrometry. Understanding whether a complex is homomeric helps interpret its assembly, mechanism, and potential vulnerabilities.