The β-Arrestins: Multifunctional Regulators of G Protein-coupled Receptors

The beta-arrestins (beta arrs) are versatile, multifunctional adapter proteins that are best known for their ability to desensitize G protein-coupled receptors (GPCRs), but also regulate a diverse array of cellular functions. To signal in such a complex fashion, beta arrs adopt multiple conformations and are regulated at multiple levels to differentially activate downstream pathways. Recent structural studies have demonstrated that beta arrs have a conserved structure and activation mechanism, with plasticity of their structural fold, allowing them to adopt a wide array of conformations. Novel roles for beta arrs continue to be identified, demonstrating the importance of these dynamic regulators of cellular signaling.