Here's how it works:
1. Proteins synthesized in the rough ER are packaged into transport vesicles.
2. These vesicles bud off the ER and travel to the Golgi apparatus.
3. The Golgi apparatus is a stack of flattened membrane-bound sacs (cisternae). As the vesicles move through the Golgi, the proteins they carry undergo various modifications:
* Glycosylation: Adding sugar molecules to the protein, which can affect its folding, stability, and function.
* Phosphorylation: Adding phosphate groups, which can activate or deactivate the protein.
* Proteolysis: Cutting the protein into smaller, functional units.
* Sorting and packaging: The Golgi sorts proteins into different types of vesicles for delivery to different destinations within the cell or for secretion outside the cell.
Think of the Golgi apparatus as a cellular "post office" that receives packages from the ER, modifies and sorts them, and then sends them to their final destination.
