Final answer:
The protein would be found in the rough endoplasmic reticulum (RER) just after it is produced in the cell. From the RER, it goes through the Golgi apparatus before being secreted from the cell.
Step-by-step explanation:
The protein would be found in the rough endoplasmic reticulum (RER) just after it is produced in the cell. The RER is a membrane-bound organelle with ribosomes on its surface, where protein synthesis occurs.
Once the protein is produced, it remains bound to the membrane of the RER. The membrane of the RER then pinches off to form a transport vesicle containing the protein. This vesicle fuses with the cis face of the Golgi apparatus, where the protein is found on the membrane and travels along the cisternae of the Golgi.
Finally, when the protein reaches the trans face of the Golgi apparatus, it gets packaged into a secretory vesicle that sends the protein to the plasma membrane, allowing it to be secreted from the cell.