Mahdavi V, Hynes R O
Biochim Biophys Acta. 1979 Mar 7;583(2):167-78. doi: 10.1016/0304-4165(79)90424-0.
Virally transformed cells show an increased production of proteolytic enzymes. These might be involved in transformation-dependent alterations of cell surface glycoproteins. The possibility arises that some of these proteases might be membrane-bound. To investigate this possibility, we have undertaken a comparative study of the reactivity of intact normal and transformed cells with the tritium labelled protease inhibitor diisopropylfluorophosphate, in parallel with fibrinolytic assays. Using these two approaches in concert, it was possible to identify and localize in the transformed cells several proteases which were present in the particulate cell fraction and were probably membrane bound. In particular, a diisopropylfluorophosphate-reactive polypeptide of 62,000 was increased 5--8-fold on transformation. It comigrated with a fibrinolytic activity. Other particle-bound activities were also detected. While diisopropylfluorophosphate-labelling can be useful for detecting proteases inside cells, it does not appear to be specific for surface proteases.
病毒转化细胞显示出蛋白水解酶产量增加。这些酶可能参与细胞表面糖蛋白的转化依赖性改变。由此产生一种可能性，即其中一些蛋白酶可能是膜结合的。为了研究这种可能性，我们对完整的正常细胞和转化细胞与氚标记的蛋白酶抑制剂二异丙基氟磷酸酯的反应性进行了比较研究，并同时进行了纤维蛋白溶解测定。协同使用这两种方法，有可能在转化细胞中鉴定并定位几种存在于颗粒细胞部分且可能是膜结合的蛋白酶。特别是，一种分子量为62,000的二异丙基氟磷酸酯反应性多肽在转化后增加了5至8倍。它与一种纤维蛋白溶解活性迁移在一起。还检测到了其他颗粒结合活性。虽然二异丙基氟磷酸酯标记可用于检测细胞内的蛋白酶，但它似乎对表面蛋白酶不具有特异性。
