β-arrestins and G protein-coupled receptor trafficking.

Nonvisual arrestins (β-arrestin-1 and β-arrestin-2) are adaptor proteins that function to regulate G protein-coupled receptor (GPCR) signaling and trafficking. β-arrestins are ubiquitously expressed and function to inhibit GPCR/G protein coupling, a process called desensitization, and promote GPCR trafficking and arrestin-mediated signaling. β-arrestin-mediated endocytosis of GPCRs requires the coordinated interaction of β-arrestins with clathrin, adaptor protein 2 (AP2), and phosphoinositides. These interactions are facilitated by a conformational change in β-arrestin that is thought to occur upon binding to a phosphorylated activated GPCR. In this review, we provide an overview of the key interactions involved in β-arrestin-mediated trafficking of GPCRs.