Once across the membrane, the signal peptide is cleaved by the signal peptidase and the process protein is released. 信号肽是疏水的，与膜上结合的蛋白接近，拉着后面的亲水多肽跨膜，一旦跨过膜，即被信号肽酶切除，释放出加工的蛋白。
Signal peptides' structures and functions, signal sequence traps and the proteins expressions in prokaryote and eukaryote expression systems were illustrated in the article. 就信号肽的结构和功能，信号肽的捕获方法及其在原核表达系统和真核表达系统中表达外源蛋白质的应用做一些介绍。
