Sphingosine Kinase Interacting Protein is an A-Kinase Anchoring Protein Specific for Type I cAMP-Dependent Protein Kinase
Sphingosine Kinase Interacting Protein is an A-Kinase Anchoring Protein Specific for Type I cAMP-Dependent Protein Kinase
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DOI：
10.1002/cbic.201000058
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发表时间：
2010-05-03
期刊：
影响因子：
3.2
通讯作者：
Scholten, Arjen
中科院分区：
文献类型：
--
作者：
Kovanich, Duangnapa;van der Heyden, Marcel A. G.;Scholten, Arjen
激酶和磷酸酶的区室化在第二信使介导的信号事件的特异性中起重要作用。cAMP依赖性蛋白激酶的定位通过其调节亚基（PKA-R）与多功能A激酶锚定蛋白（AKAP）家族的相互作用介导。大多数AKAP与PKA-RII强烈结合，而有些对PKA-RI和PKA-RII具有双重特异性;然而，迄今为止还没有哺乳动物PKA-RI特异性AKAP被分配。这主要归因于观察到PKA-RI比更重区室化的PKA-RII更胞质化。最近，哺乳动物心脏组织中cAMP相互作用组的化学蛋白质组学筛选鉴定出鞘氨醇激酶1型相互作用蛋白（SKIP，SPHKAP）为推定的新型AKAP。生物化学表征表明SPHKAP可以被认为是第一个优先结合PKA-RI α的哺乳动物AKAP。重组人SPHKAP作为RI特异性AKAP发挥作用，其利用特征性AKAP两亲性螺旋进行相互作用。利用特异性cAMP树脂的差异结合特性的进一步化学蛋白质组学筛选证实了SPHKAP直接在哺乳动物心脏和脾脏组织中对PKA-RI的内源性特异性。免疫定位研究表明，重组SPHKAP在细胞质中表达，其中PKA-RI α也主要驻留。将SPHKAP的两亲性螺旋与PKA-RI-或PKA-RII-特异性锚定结构域的肽模型进行比对，表明其主要仅具有PKA-RI α特征。作为第一个哺乳动物PKA-RI特异性AKAP。SPHKAP是一个非常有前途的模型，用于研究较少探索的胞质PKA-RI信号传导节点的功能。
The compartmentalization of kinases and phosphatases plays an important role in the specificity of second-messenger-mediated signaling events. Localization of the cAMP-dependent protein kinase is mediated by interaction of its regulatory subunit (PKA-R) with the versatile family of A-kinase-anchoring proteins (AKAPs). Most AKAPs bind avidly to PKA-RII, while some have dual specificity for both PKA-RI and PKA-RII; however, no mammalian PKA-RI-specific AKAPs have thus far been assigned. This has mainly been attributed to the observation that PKA-RI is more cytosolic than the more heavily compartmentalized PKA-RII. Chemical proteomics screens of the cAMP interactome in mammalian heart tissue recently identified sphingosine kinase type 1-interacting protein (SKIP, SPHKAP) as a putative novel AKAP. Biochemical characterization now shows that SPHKAP can be considered as the first mammalian AKAP that preferentially binds to PKA-RI alpha. Recombinant human SPHKAP functions as an RI-specific AKAP that utilizes the characteristic AKAP amphipathic helix for interaction. Further chemical proteomic screening utilizing differential binding characteristics of specific cAMP resins confirms SPHKAPs endogenous specificity for PKA-RI directly in mammalian heart and spleen tissue. Immunolocalization studies revealed that recombinant SPHKAP is expressed in the cytoplasm, where PKA-RI alpha also mainly resides. Alignment of SPHKAPs' amphipathic helix with peptide models of PKA-RI- or PKA-RII-specific anchoring domains shows that it has largely only PKA-RI alpha characteristics. Being the first mammalian PKA-RI-specific AKAP with. cytosolic localization, SPHKAP is a very promising model for studying the function of the less explored cytosolic PKA-RI signaling nodes.