Molecular cloning of brain-specific GD1α synthase (ST6GalNAc V) containing CAG/glutamine repeats
Molecular cloning of brain-specific GD1α synthase (ST6GalNAc V) containing CAG/glutamine repeats
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DOI：
10.1074/jbc.274.43.30557
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发表时间：
1999-10-22
影响因子：
4.8
通讯作者：
Furukawa, K
中科院分区：
文献类型：
--
作者：
Okajima, T;Fukumoto, S;Furukawa, K
通过表达序列标签的BLAST分析鉴定了小鼠CMP-NeuAc：β-N-乙酰氨基半乳糖α 2，6-唾液酸转移酶（ST 6 GalNAc）亚家族的新成员，命名为ST 6 GalNAc V。ST 6 GalNAc V的最长cDNA克隆的序列编码II型膜蛋白，其具有包含胞质结构域的8个氨基酸、包含跨膜区的21个氨基酸和包含催化结构域的306个氨基酸。预测的氨基酸序列显示与先前克隆的ST 6 GalNAc III和IV的同源性，在这三种酶中具有唾液酸基序L和S中的共同氨基酸序列。在茎区发现11个CAG重复序列。在表达载体中用ST 6 GalNAc V转染的L细胞的蛋白A和提取物的融合蛋白显示出几乎专门针对GM 1b的α 2，6-唾液酸转移酶的酶活性，但不针对糖蛋白。唾液酸酶处理和薄层层析免疫染色显示产物为GD 1 α。北方杂交结果表明，该基因的三个转录本在脑组织中特异性表达。它的结论是，这种酶是参与合成的GD 1 α在神经组织中，和CAG重复可能有影响的神经退行性疾病。
A novel member of the mouse CMP-NeuAc: beta-N-acetylgalactosaminide alpha 2,6-sialyltransferase (ST6GalNAc) subfamily, designated ST6GalNAc V, was identified by BLAST analysis of expressed sequence tags. The sequence of the longest cDNA clone of ST6GalNAc V encoded a type II membrane protein with 8 amino acids comprising the cytoplasmic domain, 21 amino acids comprising the transmembrane region, and 306 amino acids comprising the catalytic domain. The predicted amino acid sequence showed homology to the previously cloned ST6GalNAc III and IV, with common amino acid sequences in sialyl motifs L and S among these three enzymes. Eleven CAG repeats were found in the stem region. A fusion protein with protein A and extracts from L cells transfected with ST6GalNAc V in a expression vector showed enzyme activity of alpha 2,6-sialyltransferase almost exclusively for GM1b, but not toward glycoproteins. Sialidase treatment and thin layer chromatography immunostaining revealed that the product was GD1 alpha. Northern blotting revealed that three transcripts of the gene were expressed specifically in brain tissues. It is concluded that this enzyme is involved in the synthesis of GD1 alpha in the nervous tissues, and the CAG repeats may have implications in neurodegenerative diseases.