Organizing a functional junctional complex requires specific domains of the Drosophila MAGUK Discs large
Organizing a functional junctional complex requires specific domains of the Drosophila MAGUK Discs large
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DOI：
10.1101/gad.11.23.3242
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发表时间：
1997-12-01
影响因子：
10.5
通讯作者：
Bryant, PJ
中科院分区：
文献类型：
--
作者：
Hough, CD;Woods, DF;Bryant, PJ
大圆盘（Dlg）是第一个被鉴定出的越来越重要的一类蛋白质的成员，这种蛋白质被称为膜相关鸟苷酸激酶同源物（MAGUKs），它通常集中在细胞连接处，含有不同的肽结构域，称为PDZ1-3， SH3， HOOK和GUK。Dlg定位于上皮细胞分离连接和神经元突触连接形成所需的肛门，在缺乏Dlg的情况下，上皮细胞失去组织并过度生长。我们通过构建表达该蛋白改变形式的转基因果蝇，在体内测试了Dlg每个结构域的功能。在第一批实验中，每个结构域都被检查了其正确靶向表位标记的Dlg到预先存在的分离连接的能力。根据这些结果，Hook结构域是蛋白质定位到细胞膜所必需的，PDZ2是限制蛋白质到分隔连接所必需的。在第二组实验中，每个结构域都测试了其在生长调节和上皮结构组织中的作用。这些结果表明，PDZ1和GUK在功能上显然是不需要的，PDZ2和PDZ3在生长调节中是必需的，而在上皮结构中则不需要，SH3和HOOK在功能的其他方面是必不可少的。结果证明了Dlg的功能模块化，并阐明了单个MAGUK结构域在调节上皮组织结构和生长中的功能。
Discs large (Dlg) was the first identified member of an increasingly important class of proteins called membrane-associated guanylate kinase homologs (MAGUKs), which are often concentrated at cell junctions and contain distinct peptide domains named PDZ1-3, SH3, HOOK, and GUK. Dlg is localized at anal required for the formation of both septate junctions in epithelial cells and synaptic junctions in neurons, In the absence of Dlg, epithelia lose their organization and overgrow. We tested the functions of each domain of Dlg in vivo by constructing transgenic flies expressing altered forms of the protein. in the first sea of experiments each domain was examined for its ability to correctly target an epitope-tagged Dlg to pre-existing septate junctions. Based on these results the Hook domain is necessary for localization of the protein to the cell membrane and the PDZ2 is required for restricting the protein to the septate junction. In the second set of experiments each domain teas tested for its role in growth regulation and organization of epithelial structure. These results show that PDZ1 and GUK are apparently dispensable for function, PDZ2 and PDZ3 are required for growth regulation but not for epithelial structure, and SH3 and HOOK are essential for bath aspects of function. The results demonstrate the functional modularity of Dlg and clarify the functions of individual MAGUK domains in regulating the structure and growth of epithelial tissue.