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34 Cards in this Set
- Front
- Back
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What are GAG's?
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Glycosaminoglycans
long, unbranched and contain repeating disaccharide unit Most abundant polysaccharide in the body |
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what is used to form GAGs?
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Heteropolysaccharides
contain 13 different monosaccharides and monosaccharide derivatives Glucuronic acid Iduronic acid Galactose N-acetylglucosamine N0acetylgalactoseamine |
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What is the function of GAG's?
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highly negatively charged with extended conformation that imparts high viscosity to a solution:
Synovial fluid & Cartilage The rigidity provides structural integrity to cells and provides passageways between cells allowing for cell migration |
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where are GAGs primarily located?
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surface of cell's or in the ECM
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why are GAGs ideal for lubricating fluids in the joints?
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Low compressibility
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How many different kinds of GAGs do we produce?
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6
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what makes each GAG distinctive?
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Repeating disaccharide unit makes them distinctive
One of the monosaccharides in the disaccharide is always an AMINO sugar |
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what is the most prevalent GAG?
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Chondrotin sulfate
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what GAG has the highest negative charge?
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Heparin
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What GAG has been successfully used in supplement form to help improve human cartilage formation?
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Chondrotin sulfate
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What are PROTEOGLYCANS?
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GAGs attached to a protein backbone
Carbohydrate composition is up to 97% more carbohydrate than protein |
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how is the carbohydrate attached to the protein in a proteoglycan?
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O-linked
attached to protein via hydroxyl group of serine |
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what are the functions of Proteoglycans?
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Structural: elastic space filler
Limit diffusion of macromolecules Impede passage of microbes Acts a lubricants of joints Regulate cell motility and adhesion Sequestration of growth factors, local enzymatic action Present hormones to cell surface receptors |
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How are proteoglycans formed?
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Protein is synthesized and carbohydrate is added in rER
GAGs are synthesized in the golgi and then added to the carbohydrate that has already been attached to the serine group in the protein using a covalent glycosidic bond Addition of sulfate to the GAGs also occurs in the golgi Hyaluronic acid and the proteoglycans are secreted from the cell Outside of the cell the proteoglycan is attached to hyaluronic acid using two linker glycoproteins |
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What proteoglycan is used to make cartilage?
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Aggrecan
the biggest GAG one of two ECM proteoglycans |
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How is cartilage formed?
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Hyaluronana backbone, linker proteins attach to core proteins, GAGs attach to core proteins
Hyaluronate is the backbone but it is not used to synthesize the proteoglycans that will be attached to it. Assembly of the proteoglycans occurs outside the cell |
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How does cartilage work?
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The GAGs are highly negatively charged
Water is attracted Water surrounds the cartilage and is squeezed out and goes back in with compression. It absorbs the shock |
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What are GLYCOPROTEINS?
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mostly protein, oligosaccharide chain is covalently attached
O-linked or N-linked Oligosaccharides are used Sialic acid is very common component of Glycoproteins Fucose Dolichol is used to attach carbohydrate to protein as the protein is being synthesized in the rER (N-linked) |
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Where does most of the processing of a Glycoprotein occur?
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in the ER
some occurs in the Golgi |
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what are the functions of Glycoproteins?
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structural: collagens
lubricants: mucins Transport: transferrin Immune: immunoglobins, blood group determinants Hormone & cytokine: HCG & TSH Enzyme: alkalline phosphatase Blood clotting: fibrinogen Cell surface recognition: Lectins |
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compare and contrast proteoglycans vs. glycoproteins.
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Proteoglycans:
1. mostly carbohydrate 2. GAGs 3. O-linked to serine 4. NO SIALIC acid 5. Xylose (attached to serine) Glycoproteins 1. Mostly protein 2. Oligosaccharides 3. O-linked (serine, threonine, hydroxylysine) 4. N-linked (Asparagine) 5. Sialic acid 6. Fucose 7. Dolichol (N-linked) |
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what is SELECTIN?
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an animal glycoprotein (animal lectins)
-lectins are sugar binding proteins |
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Are all lectins glycoproteins?
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NO
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How many types of Lectins are present in humans?
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3
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what is an L-selectin ?
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produced by WBCs and allows them to attach to blood vessels and then enter the tissues
-first step of plaque formation |
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what are P-selectins?
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produced by platelets and allows them to aggregate on endothelial cells to start blood clot formation process. Recruits WBCs
-always being made |
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what are E-selectins?
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helps recruit WBCs to the site of injury
-have to be made: the gene coding for it has to be turned on |
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What is Integrin?
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selectins allow WBCs to tether and roll along the wall of blood vessels but integrin holds them so that they can move into the intima
-FUCOSE is an important component of the oligosaccharides that are used to form the 24 different integrins |
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what is an important component of the oligosaccharides used to form integrins?
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FUCOSE
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What is RICIN?
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Ricin is one of the deadliest toxins known to man
Ricin inhibits protein synthesis is cells |
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how does Ricin inhibit Protein synthesis in cells?
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inhibits the binding of elongation factor 2 to the 28S ribosome which inhibits protein synthesis
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what is the mortality rate related to ricin ingestion?
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85%
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what do people consume that has ricin in it?
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raw Castro beans
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how does cooking castro beans make them safe to eat?
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heating the ricin denatures it and destroys it's toxicity
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