Endoplasmic reticulum Endoplasm is the inner part of the cytoplasm of a cell. Reticulum means a fine network. So endoplasmic reticulum is an interlinked network of cisternae (membrane disks), vesicles (intracellular transport sacs) and tubules inside a eukaryotic cell. There are two types of endoplasmic reticulum (ER) Smooth ER and Rough ER Rough ER is named for the presence of ribosomes along its membrane and is the source of proteins. Smooth ER lacks ribosomes and is responsible for lipid synthesis and processes a variety of metabolic processes such as drug detoxification. There are two types of ER - rough, which is coated with ribosomes, and smooth, which isn't. Rough ER is the site of protein synthesis. The smooth ER is where the vesicles carrying newly synthesized proteins (from the rough ER) are budded off.Rough Endoplasmic Reticulum The rough endoplasmic reticulum manufactures membranes and secretory proteins. In leukocytes the rough ER produces antibodies. In pancreatic cells the rough ER produces insulin. The rough and smooth ER are usually interconnected and the proteins and membranes made by the rough ER move into the smooth ER to be transferred to other locations. The prime rough endoplasmic reticulum function is the production and processing of specific proteins at ribosomal sites that are later exported. The ribosomes in the rough endoplasmic reticulum do their job and create proteins which are then sent in to the rough endoplasmic reticulum for advanced processing As I said before, rough endoplasmic reticulum function involves, creation of two types of proteins. One is the type which fortifies and gets embedded into the reticulum membrane. The other types are water soluble membranes which after creation at ribosomal sites, pass through the membrane and into the lumen. The function of rough endoplasmic reticulum doesn't end there. The proteins that enter are further processed inside. Just like a two dimensional cardboard box is folded to make a box, the proteins are folded into the right three dimensional shapes and carbohydrates may be added. Once the folding is complete, they are ready for delivery. The folding is made possible by chaperone proteins present in the lumen. The next rough endoplasmic reticulum function is to transport these ready proteins to the sites where the are required. They may also be sent to the Golgi bodies for further advanced processing, through vesiclesSmooth Endoplasmic Reticulum The smooth ER has a wide range of functions including carbohydrate and lipid synthesis. It serves as a transitional area for vesicles that transport ER products to various destinations. In liver cells the smooth ER produces enzymes that help to detoxify certain compounds. In muscles the smooth ER assists in the contraction of muscle cells, and in brain cells it synthesizes male and female hormones. Smooth endoplasmic reticulum functions include carbohydrate metabolism, regulation of calcium ions, synthesis of steroids and lipids, drug detoxification, metabolism of steroids, etc. In case of muscle cells, the smooth endoplasmic reticulum stores calcium, which is released during contraction of the muscles. This cell organelle has the function of detoxification in liver cells. Smooth endoplasmic reticulum function involves the transportation of newly synthesized proteins to other locations in the cell or outside the cell. This is achieved through a process called budding, wherein the small vesicles, which contain proteins, are detached from the smooth endoplasmic reticulum and are carried to other locations. This cell organelle also aids in converting glucose-6-phosphate to glucose, which is an important step in gluconeogenesis. Smooth endoplasmic reticulum in plant cells may connect between cells through plasmodesmata Now, you know more about smooth endoplasmic reticulum, which plays an important role in various metabolic processes. Its surface area is also used for the action or storage of important enzymes.