The Functional Size of GPCRs – Monomers, Dimers or Tetramers? - GPCR Signalling Complexes: Synthesis, Assembly, Trafficking and Specificity - page 65

Chapter 4
The Functional Size of GPCRs - Monomers,
Dimers or Tetramers?

Darlaine Pétrin and Terence E. Hébert

Contents
4.1 Introduction..................................................................................................................... 68

4.2 What Crystal Structures Tell us About GPCR Dimers.................................................... 68

4.3 bAR Homodimers ........................................................................................................... 68

4.4 bAR Heterodimerization - Family Gatherings............................................................... 69

4.5 bAR Heterodimerization - Extending the GPCR Interactome....................................... 70

4.6 bAR Interactions with Other Receptor Classes .............................................................. 70

4.7 Monomer: Dimer Equilibria ........................................................................................... 70

4.8 Larger Arrays of GPCRs? ............................................................................................... 71

4.9 Biosynthetic Considerations in Receptor Dimerization and Oligomerization................ 74

References ................................................................................................................................ 77

Abstract In almost 16 years since the word “dimer” was used in a publication to
describe the organization of G protein-coupled receptors (GPCRs), a large number
of studies have since weighed in on this notion. Are native, functional GPCRs
monomers, dimers or as some would suggest even higher order structures? Here, we
review some of the latest evidence regarding the organization of these receptors in
both homo- and hetero-oligomeric formats, with a particular focus on b -adrenergic
receptors. This is particularly important for understanding the allosteric nature of
receptor/receptor interactions. It is likely that, over the course of evolution, mecha-
nisms have come into play using all of the possible variations in receptor/receptor
stoichiometry, depending on the cell and the physiological context in question.
Finally, we provide some data that suggests that higher order structures of GPCRs,
as with dimers themselves are probably assembled in the ER.

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