Proline-directed phosphorylation of human Tau protein.
Proline-directed phosphorylation of human Tau protein.
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DOI：
10.1016/s0021-9258(18)41710-3
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发表时间：
1992-11
期刊：
影响因子：
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通讯作者：
Richard VullietSO;Mitchell Halloran;Ruedi;Braunll;Alan;Smith;Gloria Lee
中科院分区：
文献类型：
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作者：
Richard VullietSO;Mitchell Halloran;Ruedi;Braunll;Alan;Smith;Gloria Lee
微管相关蛋白tau的一级序列包含序列-X-Ser/Thr-Pro-X-的多个重复，该序列是脯氨酸指导的蛋白激酶（p34 cdc 2/p58 cyclin A）的共有序列。当在体外被脯氨酸导向的蛋白激酶磷酸化时，发现tau蛋白掺入高达4.4 mol磷酸盐/mol蛋白质。胰蛋白酶磷酸肽的等电聚焦显示存在五种不同的肽，其pI值约为6.9、6.5、5.6-5.9、4.7和3.6。胰蛋白酶磷酸肽的高效液相色谱技术的映射表现出三个不同的峰。来自气相测序、氨基酸分析和磷酸氨基酸分析的数据表明，脯氨酸指导的蛋白激酶在四个位点磷酸化tau。每个位点证明在磷酸化残基的羧基末端侧存在脯氨酸残基。两个磷酸化位点位于邻近的三个重复微管结合结构域，已被发现是所需的tau蛋白在体内共定位微管。另外两个推定的磷酸化位点位于单克隆抗体Tau-1的鉴定的表位内。这些位点的磷酸化改变了tau蛋白对Tau-1抗体的免疫反应性。由于神经元微管相关蛋白tau在阿尔茨海默病中被多重磷酸化，并且Tau-1免疫反应性在神经元缠结中类似地降低并且在去磷酸化后增强，因此这些位点中的一个或多个的磷酸化可能与阿尔茨海默病中tau蛋白中的异常磷酸化位点相关。
The primary sequence of the microtubule-associated protein tau contains multiple repeats of the sequence -X-Ser/Thr-Pro-X-, the consensus sequence for the proline-directed protein kinase (p34cdc2/p58cyclin A). When phosphorylated by proline-directed protein kinase in vitro, tau was found to incorporate up to 4.4 mol of phosphate/mol of protein. Isoelectric focusing of the tryptic phosphopeptides demonstrated the presence of five distinct peptides with pI values of approximately 6.9, 6.5, 5.6-5.9, 4.7, and 3.6. Mapping of the tryptic phosphopeptides by high performance liquid chromatography techniques demonstrated three distinct peaks. Data from gas phase sequencing, amino acid analysis, and phosphoamino acid analysis suggest that proline-directed protein kinase phosphorylates tau at four sites. Each site demonstrates the presence of a proline residue on the carboxyl-terminal side of the phosphorylated residue. Two phosphorylation sites are located adjacent to the three-repeat microtubule-binding domain that has been found to be required for the in vivo co-localization of tau protein to microtubules. Two other putative phosphorylation sites are located within the identified epitope of the monoclonal antibody Tau-1. Phosphorylation of these sites altered the immunoreactivity of tau to Tau-1 antibody. Since the neuronal microtubule-associated protein tau is multiply phosphorylated in Alzheimer's disease, and Tau-1 immunoreactivity is similarly reduced in neurofibrillary tangles and enhanced after dephosphorylation, phosphorylation at one or more of these sites may correlate with abnormally phosphorylated sites in tau protein in Alzheimer's disease.