The Golgi body is a cell organelle that is part of the cellular endomembrane system found in eukaryotic cells. It is also called the Golgi apparatus or Golgi complex. The function of the Golgi body includes sorting and processing proteins. After proteins are assembled in the rough endoplasmic reticulum, they travel to the Golgi body for processing and distribution throughout the cell or to an extracellular destination.
Although the structure was discovered by Camillo Golgi in the late 19th century, the function of this organele was unknown until later in the 20th century when more sophisticated microscopes became available. It was seen in both the animal and plant cells that were studied. The Golgi body is relatively large compared to other organelles, so it was clearly visible, even with the lower magnification microscopes used at the time of discovery.
A stack of membrane-enclosed disks called cisternae make up the Golgi body. Proteins can travel through these cisternae as they are processed. There are four regions in each stack, beginning with the cis-Golgi and ending with the trans-Golgi, with the medial-Golgi and the endo-Golgi in between. Each contains different enzymes. Proteins produced in the endoplasmic reticulum travel inside of vesicles that can fuse with cisternae.
Once in the Golgi body, the proteins travel from region to region and may be modified by the enzymes contained in each region. Eventually, the protein reaches the trans-Golgi where it is sorted and packaged for distribution. These proteins may stay inside of the cell that produced them, or they can be secreted, by exocytosis, out of the cell to be used elsewhere in the organism. Golgi vesicles are released from the apparatus to transport the finished proteins to their final destinations.
Another function of the Golgi body is to assist in the distribution of lipids. While the rough endoplasmic reticulum assembles proteins for modification, the smooth endoplasmic reticulum creates lipids and passes them on to the Golgi body. These lipids are rarely modified by the Golgi body, but it does facilitate their delivery.
The Golgi body is also thought to create lysosomes, which are membrane bound sacs that contain digestive enzymes found in animal cells. These enzymes are used to break down wastes or non-functioning organelles. They can also aid the immune system by engulfing bacteria or viruses.
More recently, another function of the Golgi body has been discovered. A protein called the Golgi anti-apoptotic protein has been shown to keep a cell from undergoing apoptosis before its time. Apoptosis is a programmed cell death that, when triggered early, can cause serious health problems. The Golgi body keeps cells from digesting themselves without reason.