Heteromeric

Heteromeric is an adjective used in biochemistry and molecular biology to describe macromolecular assemblies that are composed of different kinds of subunits. The term contrasts with homomeric complexes, which are built from identical subunits. Subunits are typically encoded by distinct genes and come together to form a functional complex, often through noncovalent interactions.

Heteromeric assemblies are widespread across biology. A classic example is hemoglobin, a heterotetramer consisting of two alpha and two beta chains that together transport oxygen in blood. Many enzymes and structural protein complexes also display heteromericity, with varying subunits contributing catalytic activity, regulation, or assembly.

In cell signaling and neurobiology, heteromeric receptors and channels are common. For example, ionotropic receptors such as GABA-A and nicotinic acetylcholine receptors are often heteromeric pentamers with different subunit types; NMDA receptors are typically heteromeric tetramers of GluN1 and GluN2 (and sometimes GluN3) subunits. Heteromerization also occurs among G protein-coupled receptors, where different receptor subtypes can form functional heterodimers with distinct pharmacology and signaling.

Functionally, subunit composition influences properties such as ligand binding affinity, ion selectivity, gating kinetics, trafficking, and regulatory interactions. Because of this, heteromeric assembly has important implications for physiology and for pharmacology, including the development of drugs that target specific subunit configurations.

In summary, heteromeric describes complexes built from diverse subunits, enabling a wide range of functional diversity beyond that possible with homogeneous assemblies.