Biosynthesis of dermatan sulfate -: Chondroitin-glucuronate C5-epimerase is identical to SART2
Biosynthesis of dermatan sulfate -: Chondroitin-glucuronate C5-epimerase is identical to SART2
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DOI：
10.1074/jbc.m513373200
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发表时间：
2006-04-28
影响因子：
4.8
通讯作者：
Malmström, A
中科院分区：
文献类型：
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作者：
Maccarana, M;Olander, B;Malmström, A
我们鉴定了编码软骨素-葡糖醛酸C5-差向异构酶（EC www.example.com）的基因，其在硫酸皮肤素生物合成中将D-葡糖醛酸转化为L-艾杜糖醛酸残基。从牛脾中溶解酶，并对含有主要89-kDa候选组分的类似于43，000倍纯化制剂进行胰蛋白酶肽的质谱分析。SART 2（squamous cell carcinoma antigen recognized by T cell 2）是一种在癌细胞和组织中高度表达的功能未知的蛋白质，通过覆盖26%序列的18个肽鉴定。cDNA的瞬时表达导致293 HEK细胞裂解物中差向异构酶活性增加22倍。此外，过表达细胞产生硫酸皮肤素链与20%的艾杜糖醛酸含二糖单位，相比之下，5%的模拟转染细胞。艾杜糖醛酸残基优先聚集在块中，如在天然存在的硫酸皮肤素中。考虑到发现的身份，我们建议将SART 2重命名（Nakao，M.，Shichijo，S.，今泉，T.，井上，Y.，Matsunaga，K.，山田，A.，菊池，M.，Tsuda，N.，Ohta，K.，Takamori，S.，Yamana，H.，藤田，H.，和Itoh，K.（2000）J. Immunol.164，2565 - 2574），其功能名称为软骨素-葡糖醛酸C5-差向异构酶（或DS差向异构酶）。DS差向异构酶活性普遍存在于正常组织中，尽管具有显著的数量差异。它与由C18orf4基因编码的NCAG1蛋白的一部分高度同源，与双相情感障碍有遗传联系。NCAG1还含有一个假定的硫酸软骨素磺基转移酶结构域，因此可能参与硫酸皮肤素的生物合成。硫酸皮肤素与癌症之间的功能关系尚不清楚，但可能涉及已知的艾杜糖醛酸依赖性与生长因子、选择素、细胞因子或凝血抑制剂的相互作用。
We identified the gene encoding chondroitin-glucuronate C5-epimerase ( EC 5.1.3.19) that converts D-glucuronic acid to L-iduronic acid residues in dermatan sulfate biosynthesis. The enzyme was solubilized from bovine spleen, and an similar to 43,000-fold purified preparation containing a major 89-kDa candidate component was subjected to mass spectrometry analysis of tryptic peptides. SART2 ( squamous cell carcinoma antigen recognized by T cell 2), a protein with unknown function highly expressed in cancer cells and tissues, was identified by 18 peptides covering 26% of the sequence. Transient expression of cDNA resulted in a 22-fold increase in epimerase activity in 293HEK cell lysate. Moreover, overexpressing cells produced dermatan sulfate chains with 20% of iduronic acid-containing disaccharide units, as compared with 5% for mock-transfected cells. The iduronic acid residues were preferentially clustered in blocks, as in naturally occurring dermatan sulfate. Given the discovered identity, we propose to rename SART2 ( Nakao, M., Shichijo, S., Imaizumi, T., Inoue, Y., Matsunaga, K., Yamada, A., Kikuchi, M., Tsuda, N., Ohta, K., Takamori, S., Yamana, H., Fujita, H., and Itoh, K. ( 2000) J. Immunol. 164, 2565-2574) with a functional designation, chondroitin-glucuronate C5-epimerase ( or DS epimerase). DS epimerase activity is ubiquitously present in normal tissues, although with marked quantitative differences. It is highly homologous to part of the NCAG1 protein, encoded by the C18orf4 gene, genetically linked to bipolar disorder. NCAG1 also contains a putative chondroitin sulfate sulfotransferase domain and thus may be involved in dermatan sulfate biosynthesis. The functional relation between dermatan sulfate and cancer is unknown but may involve known iduronic acid-dependent interactions with growth factors, selectins, cytokines, or coagulation inhibitors.