G-protein coupled receptor kinases

G-Protein coupled receptor kinases (GRKs), regulate the activity of G-protein coupled receptors by phosphorylating their intracellular domains after their associated G-proteins have been released and activated.

The phosphorylated serines and threonine residues act as binding sites for Arrestin proteins which prevent the reassociation of the G-proteins with their receptors, thereby preventing reactivation of the signaling pathway.