Membrane-penetrating trehalase from silkworm Bombyx mori.: Molecular cloning and localization in larval midgut
Membrane-penetrating trehalase from silkworm Bombyx mori.: Molecular cloning and localization in larval midgut
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DOI：
10.1111/j.1365-2583.2005.00581.x
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发表时间：
2005-10-01
影响因子：
2.6
通讯作者：
Yaginuma, T
中科院分区：
文献类型：
--
作者：
Mitsumasu, K;Azuma, M;Yaginuma, T
昆虫体内的主要血糖海藻糖不同于哺乳动物体内的葡萄糖。为了将海藻糖吸收到细胞中并加以利用，组织细胞具有海藻酶（EC3.2.1.28），它在细胞器膜或细胞质中催化海藻糖转化为葡萄糖。可溶性和膜结合海藻糖酶蛋白已经从昆虫中分离出来。然而，迄今为止，只有编码可溶性海藻酶的基因在昆虫中被报道。因此，可溶性海藻糖酶被认为是通过修饰而定位在细胞表面。相比之下，编码海藻糖酶的dna通过糖基磷脂酰肌醇锚点定位于顶端细胞表面，已经从哺乳动物小肠中分离出来。氨基酸序列包含一个特定的疏水区域和上游的omega位点，该位点在c端被切割为糖基磷脂酰肌醇附着。在这里，我们描述了家蚕的一个cDNA，它编码一种新的海藻酶（2型），具有一个跨膜结构域，缺乏omega位点。免疫印迹和免疫组织化学分析表明，在家蚕幼虫的中肠组织中，可溶性海藻糖酶-1主要存在于杯状细胞腔中，而膜结合海藻糖酶-2主要存在于中肠周围的内脏肌肉中。据我们所知，这是首次报道一种编码海藻糖酶的cDNA在昆虫中穿透细胞膜并进行细胞定位。
The main blood sugar in insects, trehalose, differs from glucose in mammals. To incorporate trehalose into cells and utilize it, tissue cells possess the enzyme trehalase (EC3.2.1.28), which catalyses trehalose into glucose, in the organellar membrane or in the cytoplasm. Soluble and membrane-bound trehalase proteins have been isolated from insects. To date, however, only genes encoding the soluble trehalase have been reported in insects. Soluble trehalase is therefore believed to become localized on the cell surface via modification. In contrast, cDNAs encoding trehalase localized on the apical cell surface via the glycosylphosphatidylinositol-anchor have been isolated from mammalian small intestines. The amino acid sequence contains a specific hydrophobic region and an upstream omega site, which is cleaved for glycosylphosphatidylinositol-attachment, at the C-terminus. Here, we describe a cDNA from the silkworm Bombyx mori that encodes a novel trehalase (type-2) with one transmembrane domain and lacking the omega site. Immunoblotting and immunohistochemical analyses demonstrated that in the midgut tissue of Bombyx larvae, soluble trehalase-1 is present mainly in goblet cell cavities, but membrane-bound trehalase-2 is predominantly seen on the visceral muscle surrounding the midgut. To our knowledge, this is the first report of a cDNA encoding trehalase that penetrates the cell membrane in insects and its cellular localization.