Transglutaminase type 1 and its cross-linking activity are concentrated at adherens junctions in simple epithelial cells
Transglutaminase type 1 and its cross-linking activity are concentrated at adherens junctions in simple epithelial cells
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DOI：
10.1074/jbc.274.48.34148
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发表时间：
1999-11-26
影响因子：
4.8
通讯作者：
Tsukita, S
中科院分区：
文献类型：
--
作者：
Hiiragi, T;Sasaki, H;Tsukita, S
转谷氨酰胺酶1型被确定为酪氨酸磷酸化的蛋白质从分离的连接部分的小鼠肝脏。据报道，这种酶参与角质形成细胞中蛋白质的共价交联，但其在其他细胞类型中的表达和活性尚未得到研究。北方印迹法显示，转氨酶1型在上皮组织（肺、肝和肾）中大量表达，这也通过用针对小鼠重组蛋白产生的抗体进行免疫印迹法证实。免疫印迹分离的交界部分显示，转氨酶1型浓缩在馏分不仅作为一个97 kDa的形式，但也作为各种分子量的形式交联到其他蛋白质。与这一发现一致，内源性转氨酶1型免疫荧光共定位与E-钙粘蛋白在培养的简单上皮细胞。在肝脏和肾脏中，免疫电子显微镜显示，转氨酶1型集中，但不是唯一的，在钙粘蛋白为基础的粘附连接。此外，通过体外和体内标记，转氨酶交联活性也被证明集中在简单上皮细胞的细胞间连接处。这些研究结果表明，形成共价交联的多分子复合物的转氨酶1型是一个重要的机制，维持简单的上皮细胞的结构完整性，特别是在钙粘蛋白为基础的adherens连接。
Transglutaminase type 1 was identified as a tyrosinephosphorylated protein from the isolated junctional fraction of the mouse liver. This enzyme was reported to be involved in the covalent cross-linking of proteins in keratinocytes, but its expression and activity in other cell types have not been examined. Northern blotting revealed that transglutaminase type 1 was expressed in large amounts in epithelial tissues (lung, liver, and kidney), which was also confirmed by immunoblotting with antibodies raised against mouse recombinant protein. Immunoblotting of the isolated junctional fraction revealed that transglutaminase type 1 was concentrated in the fraction not only as a 97-kDa form but also as forms of various molecular masses cross-linked to other proteins. In agreement with this finding, endogenous transglutaminase type 1 was immunofluorescently colocalized with E-cadherin in cultured simple epithelial cells. In the liver and kidney, immunoelectron microscopy revealed that transglutaminase type 1 was concentrated, albeit not exclusively, at cadherin-based adherens junctions. Furthermore, by in vitro and in vivo labeling, transglutaminase cross-linking activity was also shown to be concentrated at intercellular junctions of simple epithelial cells. These findings suggested that the formation of covalently cross-linked multimolecular complexes by transglutaminase type 1 is an important mechanism for maintenance of the structural integrity of simple epithelial cells, especially at cadherin-based adherens junctions.