MICROANATOMY

Detailed explanation-1: -Proteins are sorted into the regulated secretory pathway in the trans Golgi network, where they are packaged into specialized secretory vesicles. These secretory vesicles, which are larger than other transport vesicles, store their contents until specific signals direct their fusion with the plasma membrane.

Detailed explanation-2: -The Golgi apparatus is the sorting organelle of the cell. Proteins from the rough endoplasmic reticulum are sent to the Golgi. As the proteins move through the Golgi apparatus, they are modified and packaged into vesicles.

Detailed explanation-3: -COPII-coated vesicles transport cargo proteins from the ER to the Golgi; COPI-coated vesicles transport cargo in the retrograde direction (from the cis-Golgi back to the ER) and between Golgi cisternae; and clathrin-coated vesicles form from the plasma membrane and the TGN to fuse with endosomes or lysosomes (Fig.