Fig. (2).

Possible modulations upon GPCR dimer formation. (A) Heterodimerization can induce a change of G protein-coupling. (B) Different expression levels of heterodimers are associated with distinct diseases. (C) Activation of one receptor can promote signalling of the other receptor via positive crosstalk. (D) Activation of both receptors can lead to β-arrestin recruitment and internalization via negative crosstalk. This can lead to intracellular signalling via mitogen-activated protein kinase (MAPK). (E) Dimerization can be necessary for plasma membrane localization, e.g., by masking an endoplasmic retention signal, which will prevent the transport to the plasma membrane as monomers.