ELASTASE INHIBITOR ELAFIN IS A NEW-TYPE OF PROTEINASE-INHIBITOR WHICH HAS A TRANSGLUTAMINASE-MEDIATED ANCHORING SEQUENCE TERMED CEMENTOIN
ELASTASE INHIBITOR ELAFIN IS A NEW-TYPE OF PROTEINASE-INHIBITOR WHICH HAS A TRANSGLUTAMINASE-MEDIATED ANCHORING SEQUENCE TERMED CEMENTOIN
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DOI：
10.1093/oxfordjournals.jbchem.a124357
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发表时间：
1994-03-01
影响因子：
2.7
通讯作者：
HIROSE, S
中科院分区：
文献类型：
--
作者：
NARA, K;ITO, S;HIROSE, S
Elafin是一种新型的蛋白酶抑制剂，具有锚定序列。人弹性蛋白酶是一种对弹性蛋白酶和蛋白酶3具有特异性的强效抑制剂，在其前片段中具有独特的重复序列，富含Gln和Lys残基。前片段，被称为“cementoin”，与精囊凝固蛋白的重复元件具有高度同源性，精囊凝固蛋白被认为是前列腺转氨酶的良好底物。通过组织转氨酶交联牙骨质妥英表明，牙骨质妥英部分确实是转氨酶的优选底物。此外，在体外观察到骨水泥妥英和层粘连蛋白之间的转氨酶介导的交联，表明骨水泥妥英具有共价连接到其他细胞外基质蛋白的能力。为了确定这种类型的弹性蛋白通过牙骨质妥英部分的共价粘合是否在体内发生，我们通过蛋白质印迹法测定了气管粘膜上皮中牙骨质妥英-弹性蛋白的分子大小;这种方法的基本原理是：（i）气管是牙骨质肽-弹性蛋白的最丰富来源，如下所示，以及（ii）如果牙骨质肽-弹性蛋白与其他蛋白质共价结合，在SDS-聚丙烯酰胺凝胶电泳上，它应该作为更高M（r）种类迁移;确实在对应于50 kDa的位置检测到牙骨质妥英-弹力蛋白免疫反应性，该值远高于其单体形式的值。RNA酶保护分析和免疫组化染色显示，牙骨质妥英-弹力素密集分布在皮肤和气管中，并在胃、十二指肠和小肠中中度分布。这些定位位点与弹性纤维丰富的位置一致。这些发现表明，牙骨质妥英部分作为分子胶锚定弹力蛋白细胞外基质蛋白，以保护弹性组织。因此，弹性蛋白可能代表一类新的蛋白酶抑制剂。
Elafin was shown to be a new type of proteinase inhibitor which has an anchoring sequence. Human elafin, a potent inhibitor specific for elastase and proteinase 3, has a unique repeating sequence in its prosegment that is rich in Gin and Lys residues. The prosegment, termed ''cementoin,'' exhibits high homology with the repetitive element of seminal vesicle clotting protein, which is known as a good substrate for prostate transglutaminase. The cross-linking of cementoin by tissue transglutaminase showed that the cementoin moiety is indeed a preferable substrate for transglutaminase. In addition, transglutaminase-mediated cross-linking between cementoin and laminin was observed in vitro, suggesting that cementoin has the ability to covalently attach to other extracellular matrix proteins. To determine whether or not this type of covalent gluing of elafin through the cementoin moiety occurs in vivo, we determined the molecular size of cementoin-elafin in the trachea mucous epithelium by Western blotting; the rationale of this approach is that (i) the trachea is the richest source of cementoin-elafin, as shown below, and (ii) if cementoin-elafin is covalently associated with other proteins, it should migrate as a higher M(r) species on SDS-polyacrylalhide gel electrophoresis; cementoin-elafin immunoreactivity was indeed detected at a position corresponding to 50 kDa, a value much higher than that of its monomeric form. RNase protection analysis and immunohistochemical staining revealed that cementoin-elafin is densely distributed in the skin and trachea, and moderately in the stomach, duodenum and small intestine. These sites of localization are consistent with the locations where elastic fibers are abundant. These findings suggest that the cementoin moiety serves as molecular glue for anchoring elafin to extracellular matrix proteins in order to protect elastic tissues. Elafin may therefore represent a new class of proteinase inhibitors.