Degradation of the G Protein-coupled Receptor Kinase 2 by the Proteasome Pathway

GRK2 is a ubiquitous member of the G protein-coupled receptor kinase (GRK) family and has been shown to play a key role in determining the desensitization and resensitization patterns of a variety of G protein-coupled receptors. In this report, we show that GRK2 is actively degraded by the proteasome proteolytic pathway, unveiling a new mechanism for the rapid regulation of its expression levels. Interestingly, activation of β 2 -adrenergic receptors (β 2 AR) markedly increases GRK2 ubiquitination and degradation through the proteasome pathway. In addition, blocking GRK2 degradation notably alters β 2 AR signaling and internalization, consistent with a relevant physiological role for GRK2 proteasomal degradation. Activity-dependent modulation of GRK2 cellular levels emerges as an important mechanism for modulating the cellular response to agonists acting through G protein-coupled receptors.