G protein is the abbreviation of trimeric GTP binding regulatory protein, which is located on the cytoplasmic side of plasma membrane and consists of three subunits: Gα, Gβ and Gγ. Gβ and Gγ exist in the form of dimers, and Gα and Gβγ subunits are anchored to the plasma membrane through lipid molecules with valence of * * * respectively. Gα subunit has GTP enzyme activity and is a molecular switch protein. When the ligand binds to the receptor, the trimer G protein dissociates, and the exchange of GDP and GTP occurs. The free G α-GTP is in an activated and open state, which leads to the binding and activation of effector proteins, thus transmitting signals. When gα-GTP is hydrolyzed into gα-GDP, it is in a closed state of inactivation, and the signal transmission stops, which leads to the reassembly of trimer G protein and the recovery system enters a static state.

1, ligand (hormone) binding induces receptor conformation change;

2. Activation of receptor binding to Gα subunit;

3. The activated receptor triggers the conformational change of Gα subunit, leading to the dissociation of GDP and G protein;

4.GTP binds to Gα subunit, which leads to the dissociation of Gα subunit from receptor and Gβγ subunit;

5. The ligand-receptor complex dissociates, and the Gα subunit binds and activates the effector protein;

6.GTP is hydrolyzed into GDP, so that the Gα subunit is separated from the effector protein and recombined with the Gβγ subunit, returning to the static state of trimer G protein.