Functions of Golgi Complex

Several Functions have been attributed to the Golgi complex. Most of the functions are based either or indirect observations or deductions.

(1) Role in secretion: general. There are numerous works describing secretory products in the cisternae of the Golgi complex. In the earlier works it was not clear whether secretory products were actually synthesized in the Golgi complex or whether the complex played a secondary role in secretion.



(2) Role in protein secretion. (1) Proteins are formed on the ribosomes attached to the ER. (2) These nascent protein are then transferred into the ER. (3) From here they go to the Golgi complex. (4) In the Golgi complex the proteins are concentrated and transformed into zymogen granules. (5) The zymogen granules released from the Gogli complex migrate to the surface of the cell. .

(3) Synthesis and secretion of polysaccharides. Studies on goblet cells by autoradiography and electron microscopy have established the interrelation between protein synthesis, carbohydrates addition ant sulphation. The goblet cells of the colon produce mucigen.





(4) Sulphation. There is evidence that the Golgi complex takes part in sulphate metabolism. Autoradiography experiments on several cell types have shown that there is radioactive sulphur uptake the Golgi region. Compounds containing active sulphur are formed in a two-step process.

(5) Plasma membrane formation. Secretory granules originating from the Golgi complex fuse with the plasma membrane during exocytosis. The membrane of the granules becomes incorporated into the plasma membrane, and thus contributes to the renewal of the membrane constituents.



(6) Plant cell wall formation. The cells walls of plant are made up of fibrils which predominantly contain polysaccharides, along with some lipids and proteins. During cytokinesis a cell plate is formed between the two daughter nuclei, and has around it a membrane which later becomes the plasma membrane of the daughter cells.

(7) Lipid packaging and secretion. Fats are broken down in the digestive tract and are absorbed into the epithclial cells of the intestine as fatty acids and monoglycerides. These substances are used in the synthesis of lipids. The epithelial cells secrete chytomicrons which contain lipids in the form of lipoproteins.

(8) Acrosome formation. The acrosome vesicle lies in front of the nucleus in the sperm. The close association between the Golgi complex and acrosome formation was known since the early light microscopy studies on the subject.

(9) Lysosome formation. Primary lysosomes are formed by the Golgi complex in a manner similar to that of protein granules. Other workers have confirmed different phases of this activity.

(10) Neurosecretion. A study of neurosecretory cells of many invertebrates and vertebrates has revealed that nucrosecretory granules lie close to the Golgi complex. Precursors of neurosecretory products have been found between the lamellae of the Golgi complex.

(11) Pigment formation. In many mamalisam tumour and cancer cells the Golgi complex has also been described as the site of origin of pigment granules (melanin).The Golgi complex has also been associated with pigment formation.

(12) Regulation of fluid balance. A homology has been suggested between the Golgi complex and the contractile vacuole of lower Metazao and Protozoa. In certain Protozoa the Gogli complex is also concerned with regulation of fluid balance.


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