A heteromer is something that consists of different parts; the antonym of homomeric. Examples are:
- Ligand-gated ion channels such as the nicotinic acetylcholine receptor and GABAA 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.[3][4][5] 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 a 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 can produce varying effects depending on where in the body it is released.[6][7][8]
- G protein-coupled receptors 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/A2A heteromers[9][10] and dopamine D1/D2[11] and D1/D3 heteromers[12]) or between entirely unrelated receptors such as CB1/A2A,[13] glutamate mGluR5 / adenosine A2A heteromers,[14] cannabinoid CB1 / dopamine D2 heteromers,[15] and even CB1/A2A/D2 heterotrimers where three different receptors have come together to form a heteromer.[16][17] 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.[18][19][20][21][22]
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Ciruela F, Casadó V, Rodrigues RJ, Luján R, Burgueño J, Canals M, Borycz J, Rebola N, Goldberg SR, Mallol J, Cortés A, Canela EI, López-Giménez JF, Milligan G, Lluis C, Cunha RA, Ferré S, Franco R (February 2006). "Presynaptic control of striatal glutamatergic neurotransmission by adenosine A1-A2A receptor heteromers". Journal of Neuroscience. 26 (7): 2080–7. doi:10.1523/JNEUROSCI.3574-05.2006. PMC 6674939. PMID 16481441.
Ferre S, Ciruela F, Borycz J, Solinas M, Quarta D, Antoniou K, Quiroz C, Justinova Z, Lluis C, Franco R, Goldberg SR (2008). "Adenosine A1-A2A receptor heteromers: new targets for caffeine in the brain". Frontiers in Bioscience. 13 (13): 2391–9. doi:10.2741/2852. PMID 17981720.
Marcellino D, Ferré S, Casadó V, Cortés A, Le Foll B, Mazzola C, Drago F, Saur O, Stark H, Soriano A, Barnes C, Goldberg SR, Lluis C, Fuxe K, Franco R (September 2008). "Identification of Dopamine D1–D3 Receptor Heteromers: INDICATIONS FOR A ROLE OF SYNERGISTIC D1–D3 RECEPTOR INTERACTIONS IN THE STRIATUM". The Journal of Biological Chemistry. 283 (38): 26016–25. doi:10.1074/jbc.M710349200. PMC 2533781. PMID 18644790.
Carriba P, Ortiz O, Patkar K, Justinova Z, Stroik J, Themann A, Müller C, Woods AS, Hope BT, Ciruela F, Casadó V, Canela EI, Lluis C, Goldberg SR, Moratalla R, Franco R, Ferré S (2007). "Striatal adenosine A2A and cannabinoid CB1 receptors form functional heteromeric complexes that mediate the motor effects of cannabinoids". Neuropsychopharmacology. 32 (11): 2249–59. doi:10.1038/sj.npp.1301375. PMID 17356572.
Marcellino D, Carriba P, Filip M, Borgkvist A, Frankowska M, Bellido I, Tanganelli S, Müller CE, Fisone G, Lluis C, Agnati LF, Franco R, Fuxe K (April 2008). "Antagonistic cannabinoid CB1/dopamine D2 receptor interactions in striatal CB1/D2 heteromers. A combined neurochemical and behavioral analysis". Neuropharmacology. 54 (5): 815–23. doi:10.1016/j.neuropharm.2007.12.011. PMID 18262573. S2CID 195685369.
Carriba P, Navarro G, Ciruela F, Ferré S, Casadó V, Agnati L, Cortés A, Mallol J, Fuxe K, Canela EI, Lluis C, Franco R (2008). "Detection of heteromerization of more than two proteins by sequential BRET-FRET". Nature Methods. 5 (8): 727–33. doi:10.1038/nmeth.1229. PMID 18587404. S2CID 5175118.
Fuxe K, Marcellino D, Rivera A, Diaz-Cabiale Z, Filip M, Gago B, Roberts DC, Langel U, Genedani S, Ferraro L, de la Calle A, Narvaez J, Tanganelli S, Woods A, Agnati LF (August 2008). "Receptor-receptor interactions within receptor mosaics. Impact on neuropsychopharmacology". Brain Research Reviews. 58 (2): 415–52. doi:10.1016/j.brainresrev.2007.11.007. PMID 18222544. S2CID 206344737.
Ferré S, Baler R, Bouvier M, Caron MG, Devi LA, Durroux T, Fuxe K, George SR, Javitch JA, Lohse MJ, Mackie K, Milligan G, Pfleger KD, Pin JP, Volkow ND, Waldhoer M, Woods AS, Franco R (March 2009). "Building a new conceptual framework for receptor heteromers". Nature Chemical Biology. 5 (3): 131–4. doi:10.1038/nchembio0309-131. PMC 2681085. PMID 19219011.