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G protein-coupled receptor kinases phosphorylate activated G protein-coupled receptors, which promotes the binding of an arrestin protein to the receptor. Arrestin binding to a phosphorylated, active receptor prevents receptor stimulation of heterotrimeric G protein transducer proteins, blocking their cellular signaling and resulting in receptor desensitization. Moreover Arrestin binding to a phosphorylated, active receptor also enables receptor signaling through arrestin partner proteins. Consequently the GRK/arrestin system serves as a signaling switch for G protein-coupled receptors.
GRK4 is most highly expressed in the testes, with lower amounts found in the brain, kidney and other tissues. It exists in four alternatively-spliced variants.
Polymorphisms in the GRK4 gene have been linked to both genetic and acquired hypertension, partly acting through kidney dopamine receptors.
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