What is the Golgi apparatus?

The Golgi apparatus is a membrane-bound organelle present in eukaryotic cells. Intracellularly, it is located in close proximity to the rough endoplasmic reticulum (ER) where it assists in the processing and packaging of proteins and lipid molecules into vesicles for transport.

Structurally, the Golgi is made up of a series of membrane-enclosed sacs called cisternae. Golgi cisternae can be divided into four regions: cis, medial, trans and trans-Golgi network (TGN). Proteins and lipid molecules are received at the cis region of the Golgi stack, travel through the medial and trans regions of the Golgi for processing (e.g. protein glycosylation), and then the TGN for packaging and transport.