1.

Four scenarios in which all G protein-coupled receptors interact with Gαβγ subunits that regulate standard second messenger generation and other common proteins (grey triangle, e.g. arrestin). They also interact with additional different proteins that give them unique signalling personalities. In A, the receptor interacts with filamin that itself binds additional proteins. The receptor shown in B interacts with an accessory protein (e.g. a RAMP) as well as another unique protein. The receptor shown in C has a long third intracellular loop that interacts with a unique protein (octagon), and a long C-terminus with a PDZ domain that binds a PDZ protein that itself brings additional proteins into the complex. In the scenario shown in D, the C-terminus of another membrane protein (e.g. a channel) interacts with the C-terminus of the receptor, and the receptor binds an additional protein.