Table 1.

Summary of Mammalian GRKs

GRK	Tissue Expression	Primary Target GPCR(s)	GRK Modification	Functional Effect	Reference
1	Retina	Rhodopsin	Gene ablation	Prolonged photon response and rod apoptosis	39
2	All, heart	β-AR, Angiotensin II type 1	Gene ablation	Embryonic lethality	46
			Conditional myocardial gene ablation	Enhanced inotropic β-AR sensitivity, blunted inotropic and lusitropic tachyphylaxis	48
			Myocardial overexpression	Enhanced desensitization to β-AR- or Angiotensin II-mediated effects on contractility and heart rate	50, 51
			Vascular overexpression	Impaired β-AR-mediated vasodilation	119
3	All, olfactory epithelium	α1-AR, thrombin, M2 and M3 muscarinic	Gene ablation	Loss of odorant-receptor mediated desensitization; enhanced airway smooth muscle constriction	42, 45
			Myocardial overexpression	Reduced α1B-AR signaling and mitogen-activated protein kinase (MAPK) activation	53
4	Testis, kidney, brain	Dopamine-1	Overexpression	No effect with WT GRK4γ but A142V polymorphism yields impaired natriuresis, hypertension	137
5	All, heart	β-AR, Angiotensin II type 1, M2 muscarinic	Gene ablation	Heightened response to cholinergic stimulation (e.g. hypothermia, salivation, tremor, antinociception); Diminished airway smooth muscle relaxation	43, 44
			Myocardial overexpression	Enhanced desensitization to β-AR chronotropic and inotropic effects	51
6	All	Chemokine receptor 4, Dopamine-2	Gene ablation	Impaired T-cell chemotaxis; Enhanced sensitivity to locomotor-stimulating effects of cocaine, amphetamine	45, 46
7	Retina	Cone opsin	Inhibition (antibody)	Reduced termination of phototransduction	40, 41