Processing, sorting, and transport of proteins synthesized in a human cell

Proteins made on ribosomes attached to the endoplasmic reticulum (ER) are transferred to the interior of the ER, where they are folded and chemically modified. Many of these proteins are transported to the Golgi complex in vesicles. In the Golgi, the proteins are further modified, sorted, and packaged into vesicles for delivery to other parts of the cell and are incorporated into organelles such as lysosomes or are transported to the surface for insertion into the plasma membrane. Proteins also can be packaged into vesicles for secretion.