Targeting of an a kinase-anchoring protein, AKAP79, to an inwardly rectifying potassium channel, Kir2.1
Targeting of an a kinase-anchoring protein, AKAP79, to an inwardly rectifying potassium channel, Kir2.1
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DOI：
10.1074/jbc.m101425200
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发表时间：
2001-06-08
影响因子：
4.8
通讯作者：
Leyland, ML
中科院分区：
文献类型：
--
作者：
Dart, C;Leyland, ML
蛋白激酶A（PKA）通过与A激酶锚定蛋白（AKAP）的相互作用靶向于其预期底物附近的离散亚细胞位置。离子通道代表了一组多样且重要的激酶底物，并且已经显示通过与AKAP缔合的PKA的膜靶向促进PKA介导的磷酸化和对几类离子通道的调节。在这里，我们调查AKAP 79，膜相关的多价锚定蛋白，后的功能和调制的强内向整流钾通道，Kir2.1的效果。在功能上，AKAP 79的存在增强了Kir2.1对升高的细胞内cAMP的响应，表明需要锚定在通道附近的PKA池。针对Kir2.1上的血凝素表位标签的抗体共免疫沉淀AKAP 79，表明这两种蛋白质在完整细胞内以复合物的形式存在。为了支持这一点，Kir2.1的细胞内N和C结构域的谷胱甘肽S-转移酶融合蛋白从细胞裂解物中分离AKAP 79，而谷胱甘肽S-转移酶单独不能与AKAP 79相互作用。总而言之，这些发现表明AKAP 79直接与Kir2.1离子通道相关，并可能用于将激酶锚在关键通道磷酸化位点附近。
Protein kinase A (PKA) is targeted to discrete subcellular locations close to its intended substrates through interaction with A kinase-anchoring proteins (AKAPs), Ion channels represent a diverse and important group of kinase substrates, and it has been shown that membrane targeting of PKA through association with AKAPs facilitates PKA-mediated phosphorylation and regulation of several classes of ion channel. Here, we investigate the effect of AKAP79, a membrane associated multivalent-anchoring protein, upon the function and modulation of the strong inwardly rectifying potassium channel, Kir2.1. Functionally, the presence of AKAP79 enhanced the response of Kir2.1 to elevated intracellular cAMP, suggesting a requirement for a pool of PKA anchored close to the channel. Antibodies directed against a hemagglutinin epitope tag on Kir2.1 coimmunoprecipitated AKAP79, indicating that the two proteins exist together in a complex within intact cells. In support of this, glutathione S-transferase fusion proteins of both the intracellular N and C domains of Kir2.1 isolated AKAP79 from cell lysates, while glutathione S-transferase alone failed to interact with AKAP79. Together, these findings suggest that AKAP79 associates directly with the Kir2.1 ion channel and may serve to anchor kinase enzymes in close proximity to key channel phosphorylation sites.