Strongin A Y, Collier I, Bannikov G, Marmer B L, Grant G A, Goldberg G I
Division of Dermatology, Washington University School of Medicine, St. Louis, Missouri 63110-1093.
J Biol Chem. 1995 Mar 10;270(10):5331-8. doi: 10.1074/jbc.270.10.5331.
Matrix metalloproteases are secreted by mammalian cells as zymogens and, upon activation, initiate tissue remodeling by proteolytic degradation of collagens and proteoglycans. Activation of the secreted proenzymes and interaction with their specific inhibitors determine the net enzymatic activity in the extracellular space. We have previously demonstrated that 72T4Cl can be activated by a plasma membrane-dependent mechanism specific for this enzyme. Here, we report purification of the membrane activator of 72T4Cl, which is a new metalloprotease identical to a recently cloned membrane-type matrix metalloprotease (MT-MMP). We demonstrate that activated MT-MMP acts as a cell surface tissue inhibitor of metalloprotease 2 (TIMP-2) receptor with Kd = 2.54 x 10(-9) M. The activator.TIMP-2 complex in turn acts as a receptor for 72T4Cl (Kd = 0.56 x 10(-9) M, binding to the carboxyl-end domain of the enzyme. Activation of 72T4Cl on the cell membrane provides a basic mechanism for spatially regulated extracellular proteolysis and presents a new target for prognosis and treatment of metastatic disease. The activation, purified as a tri-molecular complex of MT-MMP.TIMP2.carboxyl-end domain of 72T4Cl, is itself an activated form of MT-MMP, posing the following question: what is the mechanism of the activator's activation?
基质金属蛋白酶以酶原形式由哺乳动物细胞分泌，激活后通过对胶原蛋白和蛋白聚糖的蛋白水解降解启动组织重塑。分泌型酶原的激活及其与特异性抑制剂的相互作用决定了细胞外空间的净酶活性。我们之前已经证明72T4Cl可通过该酶特有的质膜依赖性机制被激活。在此，我们报告了72T4Cl膜激活剂的纯化，它是一种新的金属蛋白酶，与最近克隆的膜型基质金属蛋白酶（MT - MMP）相同。我们证明激活的MT - MMP作为金属蛋白酶2（TIMP - 2）受体在细胞表面发挥作用，解离常数Kd = 2.54×10⁻⁹ M。激活剂 - TIMP - 2复合物进而作为72T4Cl的受体（Kd = 0.56×10⁻⁹ M，与该酶的羧基末端结构域结合）。72T4Cl在细胞膜上的激活为空间调控的细胞外蛋白水解提供了一种基本机制，并为转移性疾病的预后和治疗提供了新的靶点。作为MT - MMP - TIMP2 - 72T4Cl羧基末端结构域的三分子复合物纯化得到的激活剂本身是MT - MMP的激活形式，这就提出了一个问题：激活剂的激活机制是什么？
