Figure 1.

GPCRs’ main cell localization. GPCRs are represented as orange proteins with carboxyl groups shown as gray dots and N-terminal groups with symbols of different colors, blue, green, red. Canonically functional GPCRs localize at the plasma membrane level (“1”), but they can also be functional on the membrane of different intracellular compartments: endosomes where their carboxyl domains face the cytosol (“2”); the Golgi apparatus, where they constitute a pre-existing receptor pool and to where they are delivered after being assembled in the perinuclear endoplasmic reticulum (“3”, “4”, respectively); the nucleolus, on the outer and inner nuclear membrane where the GPCR carboxyl domains face the cytosol or the nucleoplasm, respectively (“5”, “6”). GPCRs can also form pre-existing pools in the nuclear inner membrane with their carboxyl domain facing the nucleoplasm (“7”). Finally, GPCRs can be found in the mitochondrial outer membrane where their GPCR carboxyl domains face the intermembrane space (“8”).