What mechanism does βARK use to inhibit unwanted signaling?

The mechanism by which βARK (beta-adrenergic receptor kinase) inhibits unwanted signaling primarily involves the phosphorylation of receptors, which leads to their subsequent endocytosis. When βARK is activated by G protein-coupled receptors (GPCRs), it phosphorylates the intracellular domains of the activated receptors. This modification promotes the recruitment of β-arrestins, which not only prevent further interaction of the receptor with G proteins but also facilitate the internalization of the receptor through endocytosis.

By internalizing the receptor, βARK effectively diminishes the receptor's availability on the cell surface and thus reduces signaling downstream of the receptor, ultimately reducing cellular responses to ligands. This tightly regulates signal transduction pathways and prevents overstimulation.

The other mechanisms mentioned do not directly apply to βARK's role in modulating signaling through receptor phosphorylation and internalization. For instance, degradation of GTP is associated with GTP-binding proteins and not specifically with βARK function. Likewise, βARK does not directly bind to adenylyl cyclase nor primarily activate protein kinase A (PKA) as part of its role in inhibiting signaling, but rather its main function is through the regulation of receptor activity.