Question

If you remove the ER-retention signal from a protein that normally resides in the ER lumen, where do you predict the protein will ultimately end up?

a. The protein will be ubiquitinated and degraded in the cytosol.
b. The protein will be secreted to the extracellular space.
c. The protein will remain in the endoplasmic reticulum.
d. The protein will shuttle between the endoplasmic reticulum and the Golgi apparatus.
e. The protein will be stuck in the trans-Golgi network.

Answer 1

Without the ER-retention signal, a protein that usually stays in the ER lumen will likely be secreted out of the cell following modifications in the Golgi apparatus.

Step-by-step explanation:

If you remove the ER-retention signal from a protein that normally resides in the endoplasmic reticulum (ER) lumen, the protein will most likely be secreted to the extracellular space. Without the retention signal, the protein will not be held within the ER and will proceed along the secretory pathway. This involves moving from the ER to the Golgi apparatus where it is modified, then packaged into vesicles that fuse with the plasma membrane, releasing the protein outside the cell.