Arrestin Domain Containing Protein 4 (ARRDC4)

ARRDC4 belongs to the arrestin family. Arrestins are a small family of proteins important for regulating signal transduction.Arrestins were first discovered as a part of a conserved two-step mechanism for regulating the activity of G protein-coupled receptors (GPCRs) in the visual rhodopsin system by Hermann Kühn and co-workers and in the β-adrenergic system by Martin J. Lohse and co-workers. In response to a stimulus, GPCRs activate heterotrimeric G proteins. In order to turn off this response, or adapt to a persistent stimulus, activated receptors need to be silenced. The first step is phosphorylation by a class of serine/threonine kinases called G protein coupled receptor kinases (GRKs). GRK phosphorylation specifically prepares the activated receptor for arrestin binding.