G protein-coupled receptor kinases are a family of serine/threonine kinases that appear to play a role in receptor desensitization. Beta-adrenergic receptor kinase-1 (109635) and rhodopsin kinase (180381) are examples. They phosphorylate the activated form of the corresponding receptor, increasing its ability to interact with beta-arrestin or retinal arrestin, respectively. Binding of the arrestins to the receptors then blocks further activation of the respective signal transduction pathways.
General function
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Cellular localization
Cytoplasmic, Plasma membrane
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Ovarian function
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Expression regulated by
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Ovarian localization
Granulosa
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King DW, et al .
G-protein coupled receptor kinases (GRKs) are important regulators of signal transduction through the process of receptor desensitization and internalization. Receptors that are regulated by GRKs are members of the large family of seven-transmembrane receptors and include the follicle stimulating hormone receptor (FSHR). In granulosa cells, the FSH signaling system is responsible for cell proliferation, differentiation, and steroidogenesis. In the studies presented, we examined GRK mRNA and protein expression in nonmalignant human granulosa cells, in KGN cells, a human GCT cell line, and in a panel of human GCT samples. The KGN tumor cells express significantly less GRK4 alpha/beta protein and higher levels of GRK2 and GRK4 gamma/delta protein as compared to nonmalignant human granulosa cells. In human GCT samples, GRK4 alpha/beta protein was detected in 3 of the 13 tumor samples, whereas gamma/delta proteins expression was detected in all samples. These findings suggest that GRK protein expression is altered in GCTs and may be involved in the pathogenesis of these tumors.