The cysteine-rich domain of the secreted proprotein convertases PC5A and PACE4 functions as a cell surface anchor and interacts with tissue inhibitors of metalloproteinases
The cysteine-rich domain of the secreted proprotein convertases PC5A and PACE4 functions as a cell surface anchor and interacts with tissue inhibitors of metalloproteinases
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DOI：
10.1091/mbc.e05-06-0504
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发表时间：
2005-11-01
影响因子：
3.3
通讯作者：
Seidah, NG
中科院分区：
文献类型：
--
作者：
Nour, N;Mayer, G;Seidah, NG
蛋白转化酶PC5、PACE4和furin含有一个功能未知的c端富含半胱氨酸结构域（CRD）。我们证明了CRD赋予PC5A和PACE4结合组织金属蛋白酶抑制剂（TIMPs）和细胞表面的特性。共聚焦显微镜和生化分析表明，CRD对PC5A和PACE4的细胞表面系结至关重要，它与TIMP-2全长和c端结构域共定位和共免疫沉淀。表面结合的PC5A仅在TIMP-2缺失成纤维细胞中与TIMP-2共表达时才被观察到。在COS-1细胞中，质膜相关的PC5A可被肝素、苏拉明或肝素酶I和III以及与过量外源性TIMP-2竞争而移位。此外，PC5A和TIMP-2被证明在小鼠十二指肠和空肠的肠细胞表面以及肝窦中共定位。综上所述，PC5A和PACE4的CRD作为细胞表面锚定蛋白，有利于处理它们同源的表面锚定底物，包括内皮脂肪酶。
The proprotein convertases PC5, PACE4 and furin contain a C-terminal cysteine-rich domain (CRD) of unknown function. We demonstrate that the CRD confers to PC5A and PACE4 properties to bind tissue inhibitors of metalloproteinases (TIMPs) and the cell surface. Confocal microscopy and biochemical analyses revealed that the CRD is essential for cell surface tethering of PC5A and PACE4 and that it colocalizes and coimmunoprecipitates with the full-length and C-terminal domain of TIMP-2. Surface-bound PC5A in TIMP-2 null fibroblasts was only observed upon coexpression with TIMP-2. In COS-1 cells, plasma membrane-associated PC5A can be displaced by heparin, suramin, or heparinases I and III and by competition with excess exogenous TIMP-2. Furthermore, PC5A and TIMP-2 are shown to be colocalized over the surface of enterocytes in the mouse duodenum and jejunum, as well as in liver sinusoids. In conclusion, the CRD of PC5A and PACE4 functions as a cell surface anchor favoring the processing of their cognate surface-anchored substrates, including endothelial lipase.