Which part of the cell is involved in modifying, sorting, and packaging proteins?

The Golgi apparatus is critical in the process of modifying, sorting, and packaging proteins for transport to their destinations within or outside the cell. After proteins are synthesized in the rough endoplasmic reticulum, they are transported to the Golgi apparatus, where they undergo further modifications, such as glycosylation (adding sugar molecules) and phosphorylation (adding phosphate groups).

Once these modifications are complete, the Golgi apparatus sorts the proteins based on their final destinations—be it for secretion out of the cell, incorporation into the cell membrane, or transport to lysosomes. This sorting is facilitated by the formation of vesicles that bud off from the Golgi, carrying the proteins to their specific sites of action.

In contrast, the nucleus primarily functions as the control center of the cell, housing genetic material and overseeing cellular activities through gene expression. The rough endoplasmic reticulum is mainly involved in the initial synthesis of proteins, while the plasma membrane acts as a barrier that regulates the entry and exit of substances, rather than participating directly in protein processing and packaging. Thus, the Golgi apparatus stands out as the specialized organelle responsible for the final stages of protein handling within the cell.