The GTP (or GDP) is bound to the Gα subunit in the traditional view of heterotrimeric GPCR activation. This exchange triggers the dissociation of the Gα subunit (which is bound to GTP) from the Gβγ dimer and the receptor as a whole. However, models which suggest molecular rearrangement, reorganization, and pre-complexing of effector molecules are beginning to be accepted.[3][14][15] Both Gα-GTP and Gβγ can then activate different signaling cascades (or second messenger pathways) and effector proteins, while the receptor is able to activate the next G protein.[16]