Identification of a serpin-enzyme complex receptor on human hepatoma cells and human monocytes.
Identification of a serpin-enzyme complex receptor on human hepatoma cells and human monocytes.
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人肝癌细胞和人单核细胞上丝氨酸蛋白酶抑制剂-酶复合物受体的鉴定。
DOI：
10.1073/pnas.87.10.3753
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发表时间：
1990
影响因子：
11.1
通讯作者：
Fallon,RJ
中科院分区：
文献类型：
--
作者：
Perlmutter,DH;Glover,GI;Rivetna,M;Schasteen,CS;Fallon,RJ
α 1-抗胰蛋白酶（α 1-AT）与中性粒细胞弹性蛋白酶（丝氨酸蛋白酶抑制剂丝氨酸蛋白酶抑制剂-酶复合物的原型）的共价稳定复合物的形成与α 1-AT分子的结构重排和反应位点肽键的水解有关。产生约4-kDa羧基末端切割片段。α 1-AT-弹性蛋白酶复合物具有生物活性，具有趋化活性并介导人单核细胞和巨噬细胞中α 1-AT基因表达的增加。这表明，在与弹性蛋白酶形成复合物的过程中，α 1-AT分子的结构重排暴露了被特定细胞表面受体识别的结构域。为了检验这一假设，α 1-AT的已知三维结构和丝氨酸蛋白酶抑制剂的一级结构的比较被用于选择α 1-AT复合形式中潜在的外部暴露和高度保守的区域作为候选配体（羧基末端片段，氨基酸359-374）。我们在此表明，基于该区域序列的合成肽特异性地和饱和地结合人肝癌细胞和人单核细胞（Kd = 4.0 × 10（-8）M，每个细胞4.5 × 10（5）质膜受体），并介导α 1-AT合成的增加。肽105 Y（Ser-Ile-Pro-Pro-Glu-Val-Lys-Phe-Asn-Lys-Pro-Phe-Val-Tyr-Leu-Ile）的结合被α 1-AT-弹性蛋白酶复合物、抗凝血酶III（AT III）-凝血酶复合物、α 1-抗胰凝乳蛋白酶（α 1-ACT）-组织蛋白酶G复合物阻断，并且在较小程度上被补体成分C1-C1 s复合物阻断，但不被相应的天然蛋白质阻断。肽105 Y的结合也被具有对应于丝氨酸蛋白酶抑制剂AT III和α 1-ACT的羧基末端片段的序列的肽阻断，但不被具有α 1-AT的最末端氨基末端序列的肽阻断。结果还表明，肽105 Y抑制125 I标记的α 1-AT-弹性蛋白酶复合物的结合。因此，这些研究证明了一种丰富的、相对高亲和力的细胞表面受体，其识别丝氨酸蛋白酶抑制剂-酶复合物（SEC受体）。该受体能够调节至少一种丝氨酸蛋白酶抑制剂α 1-AT的产生。由于配体特异性与先前描述的丝氨酸蛋白酶抑制剂-酶复合物的体内清除相似，SEC受体也可能参与某些丝氨酸蛋白酶抑制剂-酶复合物的清除。
Formation of the covalently stabilized complex of alpha 1-antitrypsin (alpha 1-AT) with neutrophil elastase, the archetype of serine proteinase inhibitor serpin-enzyme complexes, is associated with structural rearrangement of the alpha 1-AT molecule and hydrolysis of a reactive-site peptide bond. An approximately 4-kDa carboxyl-terminal cleavage fragment is generated. alpha 1-AT-elastase complexes are biologically active, possessing chemotactic activity and mediating increases in expression of the alpha 1-AT gene in human monocytes and macrophages. This suggested that structural rearrangement of the alpha 1-AT molecule, during formation of a complex with elastase, exposes a domain that is recognized by a specific cell surface receptor or receptors. To test this hypothesis, the known three-dimensional structure of alpha 1-AT and comparisons of the primary structures of the serpins were used to select a potentially exteriorly exposed and highly conserved region in the complexed form of alpha 1-AT as a candidate ligand (carboxyl-terminal fragment, amino acids 359-374). We show here that synthetic peptides based on the sequence of this region bind specifically and saturably to human hepatoma cells and human monocytes (Kd = 4.0 X 10(-8) M, 4.5 X 10(5) plasma membrane receptors per cell) and mediate increases in synthesis of alpha 1-AT. Binding of peptide 105Y (Ser-Ile-Pro-Pro-Glu-Val-Lys-Phe-Asn-Lys-Pro-Phe-Val-Tyr-Leu-Ile) is blocked by alpha 1-AT-elastase complexes, antithrombin III (AT III)-thrombin complexes, alpha 1-antichymotrypsin (alpha 1-ACT)-cathepsin G complexes, and, to a lesser extent, complement component C1 inhibitor-C1s complexes, but not by the corresponding native proteins. Binding of peptide 105Y is also blocked by peptides with sequence corresponding to carboxy-terminal fragments of the serpins AT III and alpha 1-ACT, but not by peptides having the sequence of the extreme amino terminus of alpha 1-AT. The results also show that peptide 105Y inhibits binding of 125I-labeled alpha 1-AT-elastase complexes. Thus, these studies demonstrate an abundant, relatively high-affinity cell surface receptor which recognizes serpin-enzyme complexes (SEC receptor). This receptor is capable of modulating the production of at least one of the serpins, alpha 1-AT. Since the ligand specificity is similar to that previously described for in vivo clearance of serpin-enzyme complexes, the SEC receptor may also be involved in the clearance of certain serpin-enzyme complexes.