Murga C, Esteban N, Ruiz-Gómez A, Mayor F
Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Spain.
FEBS Lett. 1997 Jun 2;409(1):24-8. doi: 10.1016/s0014-5793(97)00476-6.
beta-Adrenergic receptor kinase (beta ARK-1 or GRK2) is a key regulatory protein involved in the regulation of G-protein-coupled receptors which associates with microsomal and plasma membranes. beta gamma Subunits of G-proteins have been suggested to mediate agonist-dependent membrane translocation of beta ARK, but their possible role in maintaining the complex subcellular distribution of the kinase is not known. In this study we show that lovastatin-mediated inhibition of G gamma subunits isoprenylation in HEK-293 cells stably transfected with beta ARK1 leads to a significant release of G beta subunits to the cytosol without causing changes in total particulate beta ARK or in the association of this kinase to plasma or microsomal membrane fractions. In addition, transient overexpression of mutant forms of G gamma unable to become isoprenylated resulted in a marked sequestration of G beta to the soluble compartment, but caused no rearrangement in the distribution of cotransfected beta ARK. These results indicate that anchoring of beta ARK to cellular membranes under basal conditions is independent of the availability of heterotrimeric G-protein subunits.
β-肾上腺素能受体激酶（βARK-1或GRK2）是一种参与G蛋白偶联受体调节的关键调节蛋白，它与微粒体膜和质膜相关联。G蛋白的βγ亚基被认为介导βARK的激动剂依赖性膜转位，但其在维持激酶复杂亚细胞分布中的可能作用尚不清楚。在本研究中，我们表明，在稳定转染βARK1的HEK-293细胞中，洛伐他汀介导的Gγ亚基异戊烯化抑制导致Gβ亚基大量释放到细胞质中，而不会引起总颗粒βARK的变化，也不会导致该激酶与质膜或微粒体膜组分的结合发生变化。此外，无法进行异戊烯化的Gγ突变体的瞬时过表达导致Gβ明显隔离到可溶性区室，但不会导致共转染的βARK分布发生重排。这些结果表明，在基础条件下，βARK锚定到细胞膜上与异源三聚体G蛋白亚基的可用性无关。
