Vomund Anthony N, Majerus Elaine M
Division of Hematology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Biol Chem. 2009 Nov 6;284(45):30925-32. doi: 10.1074/jbc.M109.000927. Epub 2009 Sep 3.
ADAMTS13 is a plasma metalloprotease that cleaves ultralarge von Willebrand factor multimers to generate less thrombogenic fragments. Although this cleavage can occur at the surface of endothelial cells, it is currently unknown whether this process involves binding of the ADAMTS13 to the endothelial cell plasma membrane. Using different assay systems, we present evidence that ADAMTS13 binds to endothelial cells in a specific, reversible, and time-dependent manner with a K(d) of 58 nm. This binding requires the COOH-terminal thrombospondin type 1 repeats of the protease. Binding is inhibited in the presence of heparin and by trypsin treatment of the cells. ADAMTS13 that was prebound to endothelial cells exhibited increased proteolysis of VWF as compared with ADAMTS13 present only in solution. These data support the notion that cleavage of VWF occurs mainly at the endothelial cell surface.
ADAMTS13是一种血浆金属蛋白酶，可切割超大的血管性血友病因子多聚体以产生血栓形成性较低的片段。尽管这种切割可在内皮细胞表面发生，但目前尚不清楚该过程是否涉及ADAMTS13与内皮细胞质膜的结合。使用不同的检测系统，我们提供证据表明ADAMTS13以特异性、可逆且时间依赖性的方式与内皮细胞结合，解离常数（K(d)）为58纳米。这种结合需要该蛋白酶的COOH末端血小板反应蛋白1型重复序列。在肝素存在下以及对细胞进行胰蛋白酶处理时，结合受到抑制。与仅存在于溶液中的ADAMTS13相比，预先结合到内皮细胞上的ADAMTS13对血管性血友病因子（VWF）的蛋白水解作用增强。这些数据支持VWF的切割主要发生在内皮细胞表面这一观点。
