Cellular localization, oligomerization, and membrane association of the hereditary spastic paraplegia 3A (SPG3A) protein atlastin
Cellular localization, oligomerization, and membrane association of the hereditary spastic paraplegia 3A (SPG3A) protein atlastin
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DOI：
10.1074/jbc.m306702200
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发表时间：
2003-12-05
影响因子：
4.8
通讯作者：
Blackstone, C
中科院分区：
文献类型：
--
作者：
Zhu, PP;Patterson, A;Blackstone, C
遗传性痉挛截瘫是一组以肢体痉挛和虚弱为特征的临床异质性综合征，伴有脊髓长上降束的远端轴突变性。早发性遗传性痉挛性截瘫SPG3A是由阿特拉斯汀/人鸟氨酸结合蛋白-3基因(这里改称为阿特拉斯汀-1)突变引起的，该基因编码的是大GTP酶的动力素/Mx/鸟巢晚期结合蛋白超家族中的一个-kDa成员。Atlastin-1蛋白主要定位于大脑，在大脑皮层和海马区的锥体神经元中含量丰富。在培养的皮质神经元中，atlastin-1与高尔基体标记共定位最显著，免疫金电子显微镜显示atlastin-1主要定位于顺式高尔基体。酵母双杂交分析和免疫共沉淀研究表明，atlastin-1可以自结合，凝胶排斥层析和化学交联研究表明atlastin-1在体内以低聚物的形式存在，很可能是四聚体。膜分离和蛋白酶保护分析表明，atlastin-1是一个完整的膜蛋白，有两个预测的跨膜结构域；N-端GTP结合区和C-端结构域都暴露在细胞质中。综上所述，这些发现表明SPG3A蛋白atlastin-1是一个多聚体完整膜GTP酶，可能参与高尔基体膜动力学或囊泡运输。
Hereditary spastic paraplegias comprise a group of clinically heterogeneous syndromes characterized by lower extremity spasticity and weakness, with distal axonal degeneration in the long ascending and descending tracts of the spinal cord. The early onset hereditary spastic paraplegia SPG3A is caused by mutations in the atlastin/human guanylate-binding protein-3 gene (renamed here atlastin-1), which codes for a 64-kDa member of the dynamin/Mx/guanylate-binding protein superfamily of large GTPases. The atlastin-1 protein is localized predominantly in brain, where it is enriched in pyramidal neurons in the cerebral cortex and hippocampus. In cultured cortical neurons, atlastin-1 colocalized most prominently with markers of the Golgi apparatus, and immunogold electron microscopy revealed a predominant localization of atlastin-1 to the cis-Golgi. Yeast two-hybrid analyses and co-immunoprecipitation studies demonstrated that atlastin-1 can self-associate, and gel-exclusion chromatography and chemical cross-linking studies indicated that atlastin-1 exists as an oligomer in vivo, most likely a tetramer. Membrane fractionation and protease protection assays revealed that atlastin-1 is an integral membrane protein with two predicted transmembrane domains; both the N-terminal GTP-binding and C-terminal domains are exposed to the cytoplasm. Together, these findings indicate that the SPG3A protein atlastin-1 is a multimeric integral membrane GTPase that may be involved in Golgi membrane dynamics or vesicle trafficking.