Rosenblatt D E, Cotman C W, Nieto-Sampedro M, Rowe J W, Knauer D J
Brain Res. 1987 Jul 7;415(1):40-8. doi: 10.1016/0006-8993(87)90267-8.
In the present studies we have compared the structural and biochemical properties of human protease nexin-I (PN-I) and a protease inhibitor present in the serum-free culture fluid of normal rat brain astrocytes. The inhibitor binds to and forms covalent complexes with human urokinase and thrombin. The inhibitor has an approximate Mr = 43,000 based on the size of the complexes (deduced from SDS-PAGE) and mediates the cellular binding and uptake of the proteases to which it links. Binding is heparin sensitive and occurs on a cell surface receptor that also binds complexes formed between proteases and a well-characterized cell-secreted protease inhibitor, human PN-I. In addition, the inhibitor co-migrates with PN-I on SDS-PAGE and cross-reacts with anti-PN-I antibody on immunoblots. A similar molecule, designated NPF, is produced by C6 glioma cells in culture and has neurite promoting activity on a neuroblastoma cell line.
在本研究中，我们比较了人蛋白酶nexin-I（PN-I）和正常大鼠脑星形胶质细胞无血清培养液中存在的一种蛋白酶抑制剂的结构和生化特性。该抑制剂与人尿激酶和凝血酶结合并形成共价复合物。基于复合物的大小（从SDS-PAGE推导），该抑制剂的近似分子量为43,000，并介导与其相连的蛋白酶的细胞结合和摄取。结合对肝素敏感，发生在细胞表面受体上，该受体也结合蛋白酶与一种特征明确的细胞分泌的蛋白酶抑制剂人PN-I之间形成的复合物。此外，该抑制剂在SDS-PAGE上与PN-I共迁移，并在免疫印迹上与抗PN-I抗体发生交叉反应。一种类似的分子，称为NPF，由培养的C6胶质瘤细胞产生，对神经母细胞瘤细胞系具有促神经突生长活性。
