Final answer:
The cleavage of the signal sequence from the preprohormone forms the mature hormone, which is then packaged into secretory vesicles for export from the cell following protein synthesis, folding, and modification processes.
Step-by-step explanation:
The signal sequence is cleaved from the preprohormone prior to being packaged into secretory vesicles, forming the prohormone or mature hormone. This process is essential in the synthesis of proteins that will be secreted from the cell.
The signal sequence, typically 10-30 amino acids long, is located at the N-terminal end of the emerging polypeptide chain. As this polypeptide is translated, it interacts with the rough endoplasmic reticulum (RER) membrane and enters the lumen, where a signal peptidase cleaves the signal sequence. Afterward, additional protein folding, modification, and targeting can occur within the cisternae of the RER or Golgi apparatus.
Once the new protein acquires its three-dimensional structure and undergoes necessary modifications, it is packaged into vesicles that may fuse with the plasma membrane to release their protein content outside the cell.