67-KD ELASTIN-BINDING PROTEIN IS A PROTECTIVE COMPANION OF EXTRACELLULAR INSOLUBLE ELASTIN AND INTRACELLULAR TROPOELASTIN
67-KD ELASTIN-BINDING PROTEIN IS A PROTECTIVE COMPANION OF EXTRACELLULAR INSOLUBLE ELASTIN AND INTRACELLULAR TROPOELASTIN
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DOI：
10.1083/jcb.126.2.563
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发表时间：
1994-07-01
影响因子：
7.8
通讯作者：
RABINOVITCH, M
中科院分区：
文献类型：
--
作者：
HINEK, A;RABINOVITCH, M
67-kD弹性蛋白结合蛋白（EBP）介导细胞粘附弹性蛋白和弹性蛋白纤维组件，它是类似的，如果不是相同的，67-kD酶失活，选择性剪接β-半乳糖苷酶。后者含有与主动脉EBP和丝氨酸蛋白酶的NH 2-末端序列同源的弹性蛋白结合结构域（S-GAL）（Hinek，A.，M. Rabinovitch，E. Keeley和J.卡拉汉。1993. J. Clin. Invest. 91：1198-1205）。我们现在证实了这种同源性的功能重要性，通过显示，弹性蛋白溶解活性的代表性丝氨酸弹性蛋白酶，猪胰弹性蛋白酶，被阻止的抗体（抗S-GAL），并通过与纯化的EBP或S-GAL肽竞争。成人主动脉的免疫组化表明，EBP存在作为一个永久的组成部分，成熟的弹性纤维。这一观察结果与体外研究一起表明，EBP可以保护不溶性弹性蛋白免受细胞外蛋白水解，并有助于这种蛋白质的非凡稳定性。用抗S-GAL和抗弹性蛋白原抗体对胎羊主动脉进行双重免疫标记，在光镜和电镜下观察到平滑肌细胞（SMC）中蛋白质的胞内共定位。SMC与半乳糖孵育以使弹性蛋白原从EBP中解离，引起弹性蛋白原的细胞内聚集。通过免疫共沉淀和交联从SMC裂解物中提取原弹性蛋白/EBP复合物，并通过显示其被半乳糖分解导致原弹性蛋白被内源性丝氨酸蛋白酶降解来说明其功能意义。这表明EBP也可以作为细胞内弹性蛋白原的“伴侣”，保护这种高度疏水的蛋白质免于自聚集和蛋白水解降解。
The 67-kD elastin-binding protein (EBP) mediates cell adhesion to elastin and elastin fiber assembly, and it is similar, if not identical, to the 67-kD enzymatically inactive, alternatively spliced beta-galactosidase. The latter contains an elastin binding domain (S-GAL) homologous both to the aorta EBP and to NH2-terminal sequences of serine proteinases (Hinek, A., M. Rabinovitch, E W. Keeley, and J. Callahan. 1993. J. Clin. Invest. 91:1198-1205). We now confirm the functional importance of this homology by showing that elastolytic activity of a representative serine elastase, porcine pancreatic elastase, was prevented by an antibody (anti-S-GAL) and by competing with purified EBP or S-GAL peptide. Immunohistochemistry of adult aorta indicates that the EBP exists as a permanent component of mature elastic fibers. This observation, together with the in vitro studies, suggests that the EBP could protect insoluble elastin from extracellular proteolysis and contribute to the extraordinary stability of this protein. Double immunolabeling of fetal lamb aorta with anti-S-GAL and antitropoelastin antibodies demonstrated, under light and electron microscopy, intracellular colocalization of the proteins in smooth muscle cells (SMC). Incubation of SMC with galactosugars to dissociate tropoelastin from EBP caused intracellular aggregation of tropoelastin. A tropoelastin/EBP complex was extracted from SMC lysates by coimmunoprecipitation and cross-linking, and its functional significance was addressed by showing that its dissociation by galactosugars caused degradation of tropoelastin by endogenous serine proteinase(s). This suggests that the EBP may also serve as a ''companion'' to intracellular tropoelastin, protecting this highly hydrophobic protein from self-aggregation and proteolytic degradation.