Functions of Rough Endoplasmic Reticulum (Campbell Biology)
Many cells secrete proteins that are produced by ribosomes attached to rough ER. For example, certain pancreatic cells synthesize the protein insulin in the ER and secrete this hormone into the bloodstream. As a polypeptide chain grows from a bound ribosome, the chain is threaded into the ER lumen through a pore formed by a protein complex in the ER membrane. The new polypeptide folds into its functional shape as it enters the ER lumen. Most secretory proteins are glycoproteins, proteins with carbohydrates covalently bonded to them. The carbohydrates are attached to the proteins in the ER lumen by enzymes built into the ER membrane.
After secretory proteins are formed, the ER membrane keeps them separate from proteins in the cytosol, which are produced by free ribosomes. Secretory proteins depart from the ER wrapped in the membranes of vesicles that bud like bubbles from a specialized region called transitional ER. Vesicles in transit from one part of the cell to another are called transport vesicles; we will discuss their fate shortly.
In addition to making secretory proteins, rough ER is a membrane factory for the cell; it grows in place by adding membrane proteins and phospholipids to its own membrane. As polypeptides destined to be membrane proteins grow from the ribosomes, they are inserted into the ER membrane itself and anchored there by their hydrophobic portions. Like the smooth ER, the rough ER also makes membrane phospholipids; enzymes built into the ER membrane assemble phospholipids from precursors in the cytosol. The ER membrane expands, and portions of it are transferred in the form of transport vesicles to other components of the endomembrane system.
Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition. https://www.pearson.com/us/higher-education/series/Campbell-Biology-Series/2244849.html
Research Article: Evidence for a KATP Channel in Rough Endoplasmic Reticulum (rerKATP Channel) of Rat Hepatocytes
Date Published: May 7, 2015 Publisher: Public Library of Science Author(s): Sajjad Salari, Maedeh Ghasemi, Javad Fahanik-Babaei, Reza Saghiri, Remy Sauve, Afsaneh Eliassi, Agustin Guerrero-Hernandez. http://doi.org/10.1371/journal.pone.0125798 Abstract: We report in a previous study the presence of a large conductance K+ channel in the membrane of rough endoplasmic reticulum (RER) from rat hepatocytes incorporated into lipid … Continue reading
Research Article: Alpha-COPI Coatomer Protein Is Required for Rough Endoplasmic Reticulum Whorl Formation in Mosquito Midgut Epithelial Cells
Date Published: March 31, 2011 Publisher: Public Library of Science Author(s): Guoli Zhou, Jun Isoe, W. Antony Day, Roger L. Miesfeld, Vladimir Uversky. http://doi.org/10.1371/journal.pone.0018150 Abstract: One of the early events in midgut epithelial cells of Aedes aegypti mosquitoes is the dynamic reorganization of rough endoplasmic reticulum (RER) whorl structures coincident with the onset of blood meal … Continue reading
Functional Difference Between Smooth and Rough Endoplasmic Reticulum (Campbell Biology) Campbell Biology Smooth Endoplasmic Reticulum The smooth ER functions in diverse metabolic processes, which vary with cell type. These processes include synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions. Enzymes of the smooth ER are important in … Continue reading
Research Article: Extended Ultrastructural Characterization of Chordoma Cells: The Link to New Therapeutic Options
Date Published: December 5, 2014 Publisher: Public Library of Science Author(s): Dagmar Kolb, Elisabeth Pritz, Bibiane Steinecker-Frohnwieser, Birgit Lohberger, Alexander Deutsch, Thomas Kroneis, Amin El-Heliebi, Gottfried Dohr, Katharina Meditz, Karin Wagner, Harald Koefeler, Gerd Leitinger, Andreas Leithner, Bernadette Liegl-Atzwanger, Dagmar Zweytick, Beate Rinner, Christopher Beh. http://doi.org/10.1371/journal.pone.0114251 Abstract: Chordomas are rare bone tumors, developed from the … Continue reading
Research Article: Actin Turnover Is Required for Myosin-Dependent Mitochondrial Movements in Arabidopsis Root Hairs
Date Published: June 18, 2009 Publisher: Public Library of Science Author(s): Maozhong Zheng, Martina Beck, Jens Müller, Tong Chen, Xiaohua Wang, Feng Wang, Qinli Wang, Yuqing Wang, František Baluška, David C. Logan, Jozef Šamaj, Jinxing Lin, Wendy A. Peer. http://doi.org/10.1371/journal.pone.0005961 Abstract: Previous studies have shown that plant mitochondrial movements are myosin-based along actin filaments, which undergo … Continue reading