homomerisch

Homomerisch describes a multimeric protein complex composed of identical subunits. In contrast, a complex is heteromerisch when its subunits are non-identical. The term is widely used in biochemistry, structural biology, and pharmacology to characterize the quaternary organization of proteins, channels, enzymes, and receptors.

Many enzymes and ion channels can form homomeric assemblies; common oligomeric stoichiometries include dimers, trimers, tetramers, and pentamers. A well-known example is the homomeric alpha7 nicotinic acetylcholine receptor, a pentameric receptor composed of five identical alpha7 subunits. Bacterial aquaporins and some voltage-gated ion channels likewise form homomeric assemblies from identical subunits.

Homomeric organization often confers structural symmetry, which can simplify assembly and allow uniform binding properties across subunits, but it can limit the range of regulatory interactions that heteromeric assemblies provide. Determination can involve biochemical purification, crosslinking, native gel electrophoresis, mass spectrometry, and high-resolution structural methods such as X-ray crystallography or cryo-electron microscopy.

In genomics and proteomics, homomericity is inferred from sequence identity and structural data; identical subunits may be encoded by a single gene, or by gene family members with high similarity. Authentic homomeric status requires that subunits are identical in sequence and structure.