Which cellular structure is responsible for modifying and packaging proteins?

The cellular structure responsible for modifying and packaging proteins is the Golgi apparatus. This organelle plays a crucial role in processing proteins that have been synthesized in the endoplasmic reticulum (ER). Once proteins are synthesized, they are transported to the Golgi apparatus, where they undergo further modifications such as glycosylation (addition of sugar groups) and phosphorylation. These modifications are essential for the proper functioning of the proteins.

After processing, the Golgi apparatus sorts and packages the proteins into vesicles that transport them to various destinations, either within the cell or outside of it. This dynamic is fundamental for the secretion of proteins and for ensuring that proteins reach their correct locations, where they can perform their designated functions. The Golgi apparatus is thus considered the central hub for protein processing and distribution within the cell.