The muscarinic M3 acetylcholine receptor exists as two differently sized complexes at the plasma membrane.
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Patowary S, Alvarez-Curto E, Xu TR, Holz JD, Oliver JA, Milligan G, Raicu V
The muscarinic M3 acetylcholine receptor exists as two differently sized complexes at the plasma membrane.
Biochem J. 2013 Jun 1;452(2):303-12. doi: 10.1042/BJ20121902.
- PubMed ID
- 23521066 [ View in PubMed]
- Abstract
The literature on GPCR (G-protein-coupled receptor) homo-oligomerization encompasses conflicting views that range from interpretations that GPCRs must be monomeric, through comparatively newer proposals that they exist as dimers or higher-order oligomers, to suggestions that such quaternary structures are rather ephemeral or merely accidental and may serve no functional purpose. In the present study we use a novel method of FRET (Forster resonance energy transfer) spectrometry and controlled expression of energy donor-tagged species to show that M(3)Rs (muscarinic M(3) acetylcholine receptors) at the plasma membrane exist as stable dimeric complexes, a large fraction of which interact dynamically to form tetramers without the presence of trimers, pentamers, hexamers etc. That M(3)R dimeric units interact dynamically was also supported by co-immunoprecipitation of receptors synthesized at distinct times. On the basis of all these findings, we propose a conceptual framework that may reconcile the conflicting views on the quaternary structure of GPCRs.