Studies on Processing Endoproteases of Biologically Active Peptide Precursors

在内分泌和神经细胞中，许多生物活性多肽被合成为较大的前体，这些前体在成对的碱性氨基酸上进行有限的内切蛋白分解，得到生物活性产物。最近，六种内切酶(Furin、PC2、PC3、PC4、PACE4和PC6)被证明参与了这种类型的加工。在本研究中，我们对呋喃类化合物进行了如下研究。我们发现了一种哺乳动物细胞系，由于Furin的突变而缺乏内切蛋白降解活性。我们已经用这个细胞系证明了，在处理许多蛋白质前体的过程中，呋喃是最重要的蛋白酶。Furin主要定位于细胞内的跨高尔基网络(TGN)。我们已经证明，对于Furin的TGN定位，它的细胞质结构域是必不可少的，而这个结构域中的丝氨酸和酪氨酸残基起着重要的作用。

In endocrine and neuronal cells, many biologically active peptides are synthesized as larger precursors, which undergo limited endoproteolysis at paired basic amino acids to yield bioactive products. Recently, six endoproteases (furin, PC2, PC3, PC4, PACE4, and PC6) has been shown to be involved in this type of processing. In this study, we have shown the followings with respect to furin.1. We have discovered a mammalian cell line that lacks endoproteolytic activity due to mutations of furin. We have shown using this cell line that furin is the most important protease for processing of precursors of many proteins.2. Furin is mainly localized to the trans-Golgi network (TGN) within cells. We have shown that, for the TGN-localization of furin, its cytoplasmic domain is essential, and Ser and Tyr residues within this domain play an important role.