A heteromer is something that consists of different parts; the antonym of

homomeric Something that is composed of one repeating subunit, the antonym of heteromeric. It is often used to describe proteins made up of multiple identical repeating polypeptide chains e.g. beta galactosidase β-Galactosidase (EC 3.2.1.23, lactase, ...

. Examples are:

Biology

* Spinal neurons that pass over to the opposite side of the spinal cord. * A

protein complex A protein complex or multiprotein complex is a group of two or more associated polypeptide chains. Protein complexes are distinct from multienzyme complexes, in which multiple catalytic domains are found in a single polypeptide chain. Protein ...

that contains two or more different polypeptides.Merriam-Webster Dictionary
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Pharmacology

Ligand-gated ion channel Ligand-gated ion channels (LICs, LGIC), also commonly referred to as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as Na+, K+, Ca2+, and/or Cl− to pass through the membrane in res ...

s such as the

nicotinic acetylcholine receptor Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral ner ...

and GABA_A receptor are composed of five subunits arranged around a central pore that opens to allow ions to pass through. There are many different subunits available that can come together in a wide variety of combinations to form different subtypes of the ion channel. Sometimes the channel can be made from only one type of subunit, such as the α7 nicotinic receptor, which is made up from five α7 subunits, and so is
homomer
rather than a heteromer, but more commonly several different types of subunit will come together to form a heteromeric complex (e.g., the α4β2 nicotinic receptor, which is made up from two α4 subunits and three β2 subunits). Because the different ion channel subtypes are expressed to different extents in different tissues, this allows selective modulation of ion transport and means that a single

neurotransmitter A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell. Neuro ...

can produce varying effects depending on where in the body it is released. *

G protein-coupled receptor G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...

s are composed of seven membrane-spanning alpha-helical segments that are usually linked together into a single folded chain to form the receptor complex. However, research has demonstrated that a number of GPCRs are also capable of forming heteromers from a combination of two or more individual GPCR subunits under some circumstances, especially where several different GPCRs are densely expressed in the same neuron. Such heteromers may be between receptors from the same family (e.g., adenosine A₁/ A_2A heteromers and dopamine D₁/D₂ and D₁/ D₃ heteromers) or between entirely unrelated receptors such as CB₁/A_2A, glutamate mGluR₅ / adenosine A_2A heteromers, cannabinoid CB₁ / dopamine D₂ heteromers, and even CB₁/A_2A/D₂ heterotrimers where three different receptors have come together to form a heteromer. The ligand binding properties and intracellular trafficking pathways of GPCR heteromers usually show elements from both parent receptors, but may also produce quite unexpected pharmacological effects, making such heteromers an important focus of current research.

References

{{reflist Biochemistry Proteins

Biology

Pharmacology

See also

References