Arrestin binding to the G protein-coupled N-formyl peptide receptor is regulated by the conserved "DRY" sequence

Following activation by ligand, the N-formyl peptide receptor (FPR) undergo es processing events initiated by phosphorylation that lead to receptor des ensitization and internalization. Our previous results have shown that FPR internalization can occur in the absence of receptor desensitization, sugge sting that FPR desensitization and internalization are controlled by distin ct mechanisms. More recently, we have provided evidence that internalizatio n of the FPR occurs via a mechanism that is independent of the actions of a rrestin, dynamin, and clathrin. In the present report, we demonstrate that stimulation of the FPR with agonist leads to a significant translocation of arrestin-2 from the cytosol to the membrane. Fluorescence microscopy revea led that the translocated arrestin-2 is highly colocalized with the Ligand- bound FPR, A D71A mutant FPR, which does not undergo activation or phosphor ylation in response to ligand, did not colocalize with arrestin-2. Surprisi ngly, an R123G mutant FPR, which does not bind G protein but does become ph osphorylated and subsequently internalized, also did not bind arrestin, The se results indicate that arrestin binding is not required for FPR internali zation and demonstrate for the first time that a common motif, the conserve d "DRY" domain of G protein-coupled receptors, is essential for phosphoryla tion-dependent arrestin binding, as well as G protein activation.