Golgi Complex

The Golgi apparatus, sometimes called the Golgi complex, consists of stacks of thin, flattened vesicles or sacs. These Golgi bodies are found near the nucleus and function in as­sociation with the ER. By way of transfer vesicles, the Golgi complex receives the small membrane-covered materials produced in the ER. Many cells synthesize proteins that are larger than the active product. As an example, the Golgi complex of the beta cells of the pancreas cuts apart pro-insulin, the inactive form of insulin, into the smaller active form. The Golgi complex modifies these substances and packages them into secretory granules or vesicles. These se­cretory vesicles contain enzymes destined for export from

the cell. After appropriate signals, secretory vesicles move out of the Golgi complex into the cytoplasm, fuse to the inner side of the plasma membrane, and release their con­tents into the extracellular fluid. Figure 4-4 is a diagram of the synthesis and movement of a hormone through the rough ER and Golgi complex. In addition, the Golgi may produce large carbohydrate molecules that combine with proteins produced by the rough ER to form glycoproteins.