GRK phosphorylation specifically prepares the activated receptor for arrestin binding. Arrestin binding to the receptor blocks further G protein-mediated signaling and targets receptors for internalization, and redirects signaling to alternative G protein-independent pathways, such as β-arrestin signaling.[7][8][9][10][5] In addition to GPCRs, arrestins bind to other classes of cell surface receptors and a variety of other signaling proteins.[11]