Function in Secretion

The functioning of the Golgi apparatus as part of an integrated and interassociated endomembrane system can be appreciated most readily from the important role of the Golgi apparatus in the elaboration of protein secretions for export to the cell's exterior. The type of secretion that involves the Golgi apparatus is most appropriately referred to as exocrine secretion where materials elaborated within the cell are packaged into discrete transport packets or vesicles and discharged. Discharge is accomplished by fusion of the membranes of the vesicle with the surface membrane or plasma membrane of the cell.

To illustrate the importance of secretory mechanisms involving the Golgi apparatus, it is sufficient just to list some of the many products processed via the classical endoplasmic reticulum—Golgi apparatus—secretory vesicle—plasma membrane export route. The list includes not only many important digestive enzymes, blood constituents and hormones but most of the major food and fiber commodities of agriculture and commerce (except for starch). In this latter category are included fat and protein components of milk, cell wall materials, latex (the source of natural rubber), natural oils, collagen, and mucopolysaccharides of connectives tissues in meat, egg yolks, and storage lipids and proteins of seeds.