Endoplasmic Reticulum
The Endoplasmic Reticulum (ER) is an organelle found in all Eukaryotic cells. It is made up of a network of interconnected tubules and cisternae held together by the cytoskeleton. The ER and nuclear membrane form and enclosed internal space called the ER lumen. The Endoplasmic Reticulum is involved in many general functions in the cell. Its main function is the synthesis of both lipids and proteins and serves as site of production for most of the cells organelles, including itself.[1] Specialized Regions of ER serves as a store of Ca2+ that is used in cell signalling and muscle contraction.[2] Distinct regions of the ER become highly specialized to meet the needs of the functional Demands of the Cell. There are three types are Endoplasmic Reticulum, Smooth Endoplasmic Reticulum (SER) Rough Endoplasmic Reticulum (RER), and Sarcoplasmic Reticulum. RER is coated in ribosomes giving it its rough appearance and is involved in protein synthesis Regions of ER that lack ribosomes are called SER, however most ER is usually partly smooth and partly rough. The SER is where the vesicles carrying newly synthesied proteins bud off as well as various other metabolic processes like drug detoixification, carbohydrates and steroid metabolism and Ca2+ regulation.[3] Sarcoplasmic Reticulum is modified smooth ER specialised for the pumping and storing of Ca2+ storage.
Alberts B, Johnson A, Lewis J, Raff M, Roberts K and Walter P. (2002) Molecular Biology of the Cell, Fifth Edition, New York, Garland Science. Lodish H, (2003) Molecular Cell Biology, 5th Edition. W. H. Freeman Bittar E, (1995). Cellular Organelles, Elsevier Science, P190-211