<unk><unk><unk>  receptor kinases phosphorylate activated<unk><unk><unk>  receptors, which promotes the binding of an arrestin<unk>  to the receptor. Arrestin binding to phosphorylated, active receptor prevents receptor stimulation of heterotrimeric<unk><unk>  transducer<unk> s, blocking their cellular signaling and resulting in receptor desensitization. Arrestin binding also directs receptors to specific cellular internalization pathways, removing the receptors from the cell surface and also preventing additional activation. Arrestin binding to phosphorylated, active receptor also enables receptor signaling through arrestin partner<unk> s. Thus the<unk> RK/arrestin system serves as a complex signaling switch for<unk><unk><unk>  receptors.<unk>  and the closely related<unk> RK2 phosphorylate receptors at sites that encourage arrestin-mediated receptor desensitization, internalization and trafficking rather than arrestin-mediated signaling (in contrast to<unk> RK5 and<unk> RK6, which have the opposite effect). This difference is one basis for pharmacological biased agonism (also called functional selectivity), where a drug binding to a receptor may bias that receptor’s signaling toward a particular subset of the actions stimulated by that receptor.<unk>  is expressed broadly in tissues, but<unk> enerally at lower levels than the related<unk> RK2.<unk>  has particularly high expression in olfactory neurons, and mice lacking the ADRBK2<unk> ene exhibit defects in olfaction.<unk> ene linkage techniques were used to identify a polymorphism in the promoter of the human ADRBK2<unk> ene as a possible cause of up to 10% of cases of bipolar disorder. However, the significance of<unk>  in bipolar disorder has been controversial due to conflicting reports.<unk>  has also been implicated in regulation of dopamine receptors in Parkinson disease in animal models. Reduced expression of<unk>  has been associated with the immunodeficient WHIM syndrome in humans, and appears causative in a mouse model of the disease.
G protein-coupled receptor kinase 3
G protein-gated ion channel
Tropomyosin receptor kinase A
Hydroxycarboxylic acid receptor 2
Cyclic nucleotide–gated ion channel
Growth hormone secretagogue receptor
Type II cytokine receptor
Phosphorylase kinase, alpha 1