Recombinant O-GlcNAc transferase isoforms:: identification of O-GlcNAcase, yes tyrosine kinase, and tau as isoform-specific substrates
Recombinant O-GlcNAc transferase isoforms:: identification of O-GlcNAcase, yes tyrosine kinase, and tau as isoform-specific substrates
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DOI：
10.1093/glycob/cwj078
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发表时间：
2006-05-01
期刊：
影响因子：
4.3
通讯作者：
Hanover, JA
中科院分区：
文献类型：
--
作者：
Lazarus, BD;Love, DC;Hanover, JA
O-linked N-acetylglucosaminyltransferase （OGT）催化O-linked GlcNAc转移到多种底物蛋白的丝氨酸或苏氨酸残基上，包括核孔蛋白、转录因子以及与糖尿病和神经退行性疾病有关的蛋白。我们已经确定了OGT的两个核胞质亚型（ncOGT和sOGT）和一个定位于线粒体的亚型（mOGT）。这三种同工异构体含有相同的催化区域，但在每种酶的n端发现的四肽重复基序的数量不同。我们在大肠杆菌中以可溶性形式表达了这些OGT亚型，并利用它们鉴定了新的靶标，包括src家族酪氨酸激酶和o - glcnac酶。我们证明了一些底物蛋白，如Nup62和酪蛋白激酶II，被ncOGT和mOGT糖基化，而其他的如O-GlcNAcase和tau蛋白被ncOGT特异性修饰。mOGT对yes激酶进行了特异性修饰。OGT的短异构体（sOGT）没有糖基化任何底物，尽管它保留了一个潜在的活性催化结构域。我们的研究结果证明了重组OGT在识别新靶标方面的潜在效用，并说明了检查该酶的所有活性同工型的必要性。酪氨酸激酶和O-GlcNAcase作为OGT靶点的鉴定表明，OGT可能参与许多信号转导级联反应。
O-linked N-acetylglucosaminyltransferase (OGT) catalyzes the transfer of O-linked GlcNAc to serine or threonine residues of a variety of substrate proteins, including nuclear pore proteins, transcription factors, and proteins implicated in diabetes and neurodegenerative disorders. We have identified two nucleocytoplasmic isoforms of OGT (ncOGT and sOGT) and one isoform that localizes to the mitochondria (mOGT). These three isoforms contain identical catalytic regions but differ in the number of tetratricopeptide repeat motifs found at the N-terminus of each enzyme. We expressed each of these OGT isoforms in a soluble form in Escherichia coli and have used them to identify novel targets including the Src-family tyrosine kinase yes and O-GlcNAc-ase. We demonstrate that some substrate proteins, such as Nup62 and casein kinase II, are glycosylated by both ncOGT and mOGT, while others such as O-GlcNAcase and tau are specifically modified by ncOGT. The yes kinase was specifically modified by mOGT. The short isoform of OGT (sOGT) did not glycosylate any of the substrates tested, although it retains a potentially active catalytic domain. Our findings demonstrate the potential utility of recombinant OGT in identifying new targets and illustrate the necessity to examine all active isoforms of the enzyme. The identification of a tyrosine kinase and O-GlcNAcase as OGT targets suggests the potential for OGT participation in numerous signal transduction cascades.