- published: 20 Dec 2015
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Oligosaccharyltransferase or OST (EC 2.4.1.119) is a membrane protein complex that transfers a 14-sugar oligosaccharide from dolichol to nascent protein. It is a type of glycosyltransferase. The sugar Glc3Man9GlcNAc2 (where Glc=Glucose, Man=Mannose, and GlcNAc=N-acetylglucosamine) is attached to an asparagine (Asn) residue in the sequence Asn-X-Ser or Asn-X-Thr where X is any amino acid except proline. This sequence is called a glycosylation sequon. The reaction catalyzed by OST is the central step in the N-linked glycosylation pathway.
OST is a component of the translocon in the endoplasmic reticulum (ER) membrane. A lipid-linked core-oligosaccharide is assembled at the membrane of the endoplasmic reticulum and transferred to selected asparagine residues of nascent polypeptide chains by the oligosaccharyl transferase complex. The active site of OST is located about 4 nm from the lumenal face of the ER membrane.
It usually acts during translation as the nascent protein is entering the ER, but this cotranslational glycosylation is nevertheless called a posttranslational modification. A few examples have been found of OST activity after translation is complete. Current opinion is that post-translational activity may occur if the protein is poorly folded or folds slowly.
Khan Academy is a non-profit educational organization created in 2006 by educator Salman Khan with the aim of providing a free, world-class education for anyone, anywhere. The organization produces short lectures in the form of YouTube videos. In addition to micro lectures, the organization's website features practice exercises and tools for educators. All resources are available for free to anyone around the world. The main language of the website is English, but the content is also available in other languages.
The founder of the organization, Salman Khan, was born in New Orleans, Louisiana, United States to immigrant parents from Bangladesh and India. After earning three degrees from the Massachusetts Institute of Technology (a BS in mathematics, a BS in electrical engineering and computer science, and an MEng in electrical engineering and computer science), he pursued an MBA from Harvard Business School.
In late 2004, Khan began tutoring his cousin Nadia who needed help with math using Yahoo!'s Doodle notepad.When other relatives and friends sought similar help, he decided that it would be more practical to distribute the tutorials on YouTube. The videos' popularity and the testimonials of appreciative students prompted Khan to quit his job in finance as a hedge fund analyst at Connective Capital Management in 2009, and focus on the tutorials (then released under the moniker "Khan Academy") full-time.
Structure of the endoplasmic reticulum and Golgi body (Golgi apparatus), and how they function in secretion of proteins from the cell. Watch the next lesson: https://www.khanacademy.org/science/biology/structure-of-a-cell/tour-of-organelles/v/endomembrane-system?utm_source=YT&utm;_medium=Desc&utm;_campaign=biology Missed the previous lesson? https://www.khanacademy.org/science/biology/structure-of-a-cell/prokaryotic-and-eukaryotic-cells/v/prokaryotic-and-eukaryotic-cells?utm_source=YT&utm;_medium=Desc&utm;_campaign=biology Biology on Khan Academy: Life is beautiful! From atoms to cells, from genes to proteins, from populations to ecosystems, biology is the study of the fascinating and intricate systems that make life possible. Dive in to learn more about the many branches of biology and why...
Exit of a glycopeptide product from the binding site of the Bacterial Oligosaccharyltransferase PglB in a palmitoyl-oleoyl-phosphatidylethanolamine (POPE) membrane. PglB catalyzes the en bloc transfer of a lipid-linked oligosaccharide chain to an acceptor protein containing the (D/E-X)-N-X-S/T sequon. molcrafting.com
Nathalie Cornillie (ESR4_ETH Zurich) Nathalie Cornillie studied Biochemistry and Biotechnology at the University of Ghent, Belgium and obtained her MSci degree with a major in Biochemistry and Structural Biology. For her Master's thesis she joined the laboratory of Prof. Raimund Dutzler at the University of Zürich (Switzerland), where she worked on the expression, purification and X-ray crystallization of membrane proteins for structural studies. Now, she is interested in glycobiology and, more specifically, N-linked glycosylation. Her research focus lies in the expression and characterization of the oligosaccharyltransferase from Entamoeba histolytica and Plasmodium falciparum, which are human parasites. The oligosaccharyltransferase is the central enzyme that catalyzes N-linked glycosyl...
https://www.helpingtutors.com/ Briefly explain the roles of dolichol phosphate, flippase, and and oligosaccharyl transferase in protein glycosylation.
Speakers: Perry Nisen, M.D., Ph.D. Chief Executive Officer Donald Bren Chief Executive Chair Sanford Burnham Prebys Medical Discovery Institute Investigating Rare Diseases Through the NIH Undiagnosed Diseases Program and Network William Gahl, M.D., Ph.D. National Institutes of Health A Mouse Model Mimicking PMM2-CDG Shengfang Jin, Ph.D. Agios Pharmaceuticals Inc. New Insight into CDG Pathogenesis from Zebrafish and Stem Cell Models Richard Steet, Ph.D. University of Georgia Oligosaccharyltransferase Mutations: Role in CDG-I Reid Gilmore, Ph.D. University of Massachusetts Medical School Peters Plus Syndrome and other deficiencies in glycosylation of cysteine-rich domains Robert Haltiwanger, Ph.D. The University of Georgia Complex Carbohydrate Research Cent
Asparagine is one of the 20 most-common natural amino acids on Earth. It has carboxamide as the side-chain's functional group. It is not an essential amino acid. Its codons are AAU and AAC. A reaction between asparagine and reducing sugars or other source of carbonyls produces acrylamide in food when heated to sufficient temperature. These products occur in baked goods such as French fries, potato chips, and toasted bread. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video