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。