BIOL 302 1st Edition Lecture 24 Outline of Last Lecture I. MetabolismOutline of Current Lecture I. CarbohydratesII. GlycoproteinsIII. Mucins ( AKA mucoproteins)IV. HeteropolysaccharidesV. ProteoglycanCurrent LectureI. GlycoconjugatesA. Glycoproteins (most 1-10% carbohydrate)Cell membrane proteins, secreted proteinsB. Proteoglycans (glycosaminoglycans+ protein).C. Mostly carbohydrate (~80-95%), structural components: cartilageD. Mucins Found in mucus; lubricantsE. Mostly carbohydrate too: GalNAcII. Why glycosylate proteins?A. It increases the complexity of the proteome. Same genome can make more, different proteins.B. It directs trafficking; glycosylation can control whether a protein goes to the cell surface for secretion or to the lysosomeC. Protein folding (or lack of folding) can vary based on glycosylation stateD. Can contribute structural strengthThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.III. Linkages in GlycoproteinsA. GlycosyltransferasesB. catalyze N-and O- linked protein glycosylation IV. Protein glycosylation happens in the ER lumen and GolgiV. Your favorite protein (YFP)A. Usually glycosylated and secreted.B. The mutants you’re studying don’t secrete YFPC. What is a possible reason for this?1. The mutation changes an Arg to Ser in YFP2. A mutation in a YFP – specific glycosyltransferase prevents it from getting to the ER3. Your protein is still glycosylated, but targeted to the lysosome instead.4. A mutation in the secretion apparatus prevents all proteins from being secretedVI. N – linked sugars have a common coreA. Asn must be in the context of Asn –X – Ser or Asn –X – Thr where X can’t be ProVII. N - linked oligosaccharidesA. assembled on a specialized lipid in the ER called dolichol phosphateVIII. GlcNAc - 1- P transferaseA. uses UDP-GlcNAc to start a dolichol-phosphate oligosaccharideIX. Glycosyltransferases transfer sugarsA. UDP is a nucleotide: uridine diphosphateB. UDP-glucose is a precursor used in the biosynthesis of oligosaccharides destined to become protein modifications.X. The complex polysaccharideA. ultimately transferred to an Asn residue on the newly – glycosylated XI. EPO Stimulates the production of RBCs A. Why glycosylation?1. - Aids in proper protein folding. 2. - Provides stability by protection against proteases 3. - Involved in receptor binding.a. All people express the enzymes needed to synthesize the O antigen.XII. ABO Blood TypeA. Determined by Two Glycosyltransferases1. People with type A blood also express the GalNAc transferase that adds the extra N-acetylgalactosamine2. Those w/ type B blood express the Gal transferase that adds the extra galactose3. Those w/ type B blood express the Gal transferase that adds the extra galactose XIII. Inheritance of blood typefather - - --Blood typeCan receiveblood from↓AmotherBOA A or OAAA ABAOB B or OBBA BBBOAB A, B, AB or OOOA OBOOO OXIV. Clicker Question: Who’s a universal donor?, A universal recipient?A. AB; OB. O; AB C. O; OD. AB; ABE. There is no universal donor. XV. ProteoglycansA. Are another glycoconjugate: (polysaccharide linked to a protein or peptide)B. Can be up to 95% sugar, 5% proteinXVI. ProteoglycanA. a few proteins linked w/lots of glycosaminoglycans (disaccharide repeating units)B. Chondroitin-6-sulfate:1. D-glucuronic acid-(b 13)-N-acetyl-Dgalactosamine-6-sulfate-(b 14)C. Keratan sulfate:1. D-galactose-(b 14)-N-acetyl-D-glucosamine6-sulfate-(b 13)-XVII. HeteropolysaccharidesA. Glycosaminoglycans (disaccharide repeating units)B. Dermatan sulfate:1. -L-iduronic acid-(a 13)-N-acetyl-Dgalactosamine-4-sulfate-(b 14)C. Hyaluronic acid:1. D-glucuronic acid-(b 13)-N-acetyl-Dglucosamine-(b 14)-XVIII. Chitin is a long polymer of GlcNAcXIX. Mucins (AKA mucoproteins)A. VNTR region of the protein backbone has a high degree of glycosylation B. forces it into an extended conformationC. highly branched, variable structureXX. LectinsA. Are proteins that bind to specific oligosaccharides.1. The L - type lectins are found in the ER, leguminous plants2. The C – type lectins have a Ca ++ - binding carbohydrate recognition domain.XXI. SelectinsA. are C-type lectins that recruit immune cells to sites of injury during the immune response Selectins function in adhesion:1. Binding carbohydrates on lymph node vessels (L type)2. Binding carbohydrates on endothelium (E type)3. Binding of carbohydrates on blood platelets (P type)XXII. You try to co - culture endothelial cells with leukocytes using a new medium your undergrad made. Your leukocytes are expressing all of the correct selectins, but you aren’t seeing adhesion.A. What could be wrong?1. Lack of calcium in the medium2. Glycosidases in the medium3. Medium is hotXXIII. Errors in glycosylation interrupt protein trafficking, causing I-cell diseaseA. Carbohydrates can serve as markers to direct selected proteins to the lysozyme. In the absence of modification, enzymes are secreted. B. Result is a buildup of undigested cellular components called “inclusions” XXIV. Influenza virus infects cells by recognizing sialic acid at glycoprotein terminiXXV. Inhibition of viral glycosidase with transition state analogs limits influenza infectionXXVI. You have a sister that is resistant to influenza infection.A. What is a possible reason for this?1. Reduced cellular sialic acid levels2. Hemagglutinin-binding, neutralizing antibody3. Neuraminidase-blocking activitya. Natural transition-state analog?b. Hydrolysis or phosphorylation or glycosylation of