β-Arrestin-1 (ARRB1) is a cytoplasmic protein that belongs to the arrestin family. ARRB1 is expressed at high levels in peripheral blood leukocytes and the central nervous system. ARRB1 regulates agonist-mediated G-protein coupled receptor (GPCR) signaling by mediating both receptor desensitization and resensitization processes. ARRB1 acts as a cofactor in the beta-adrenergic receptor kinase (BARK) mediated desensitization of beta-adrenergic receptors. ARRB1 is believed to play a major role in regulating receptor-mediated immune functions. ARRB1 is involved in Toll-like receptor and IL-1 receptor signaling through the interaction with TRAF6.