Adrenergic receptor signaling and regulation

At the beginning, β-arrestin is believed to regulate desensitization of G protein-coupled receptors. However, it becomes apparent that β-arrestin is involved in not only regulation but also signal transduction by identification of many proteins interacting with β-arrestin. So far, the model of regulation and signaling of G protein-coupled receptor is built on β₂-adrenergic receptor. However, this model does not apply to all G protein-coupled receptors. The differential regulation and signaling between β₁- and β₂-adrenergic receptors is presented.