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12 Cards in this Set
- Front
- Back
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Properties of Transmembrane Protein Formation:
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1. Start and Stop HYDROPHOBIC internal signal sequences on protein
2. Both N and C terminus end up in cytosol. 3. Can form up to a 12-transmembrane protein complex. |
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Asparagine Linked Glycosylation - Properties and Main Points
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1. only occurs in the ER
2. N-linked type glycosylation 3. occurs while protein is translating and being pushed through translocation channel into ER 4. chaperones are constantly bound to the protein 5. activated oligosaccharides are made in the cytoplasm and placed on the Asn with the help of dolichol phosphate - DP flips the oligosaccharide moeity into the ER lumen, where it is further processed before being placed on the Asn 6. OST Complex put the Asn-linked oligosaccharide on the protein |
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Describe the role of Calnexin and Glucosyl-Transferase.
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After glucose trimming, Calnexin binds to the modified sugar moeity of the protein in the ER Lumen. Along with glucosidase, it snips the final glucose residues to form the final N-linked oligosaccharide on the protein. If this process does not occurr correctly, then glucosyl-transferase binds the olig-protein and enters it into the same cycle once more.
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What is the pathway that regulates how certain proteins get returned to the ER?
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1. In the Golgi, KDEL sequence on protein C-terminus binds to KDEL receptor.
2. COP I Coat forms around receptor-ligand complex. 3. Vesicle makes its way back to the ER. *The pH of the Golgi is important in this process. |
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Describe the Mannose-6-Phosphate Pathway.
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1. GlcNAc Phosphotransferase binds signal sequences on glycosylated protein and phosphorylates mannose.
2. Phosphodiesterase cleaves leaving only mannose-6-phosphate. 3. Mannose-6-Phosphate binds receptor in Golgi. 4. Clathrin coat forms. 5. Directed towards lysosome. 6. Low pH of lysosome induces receptor to dissociate from mannose-6-phosphate. 7. mannose-6-phosphate is recycled back to trans-Golgi. |
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What are some diseases that originate in the RER?
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Pseudoacrondoplasia
Cystic fibrosis Alzheimers Parkinsons Type II DM Huntington's Disease Prion Diseases Hemophilia A1 |
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Why do type II diabetics tend to continually synthesize proteins?
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They are hyperglycemic. This means the high [glucose] is putting so much stress on beta cells to make insulin, that they eventually enter apoptosis. This results in a type II diabetic turning into a type I diabetic.
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Explain the functions of BiP.
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1a. BiP binds unfolded proteins/T.M. proteins and inhibits them.
2a. Too much unfolded protein causes BiP to let go of the TM protein PERK. 3a. PERK, when free, phosphorylates eIF2a, slowing translation. 1b. BiP also binds RNAase in the nucleus. When it let's it go, the RNAase cleaves mRNA TF's and activates transcription of chaperones to fold all the unfolded proteins. 1c. BiP also binds ATF6 in the rER. When it lets it go, ATF6 travels to Golgi via COP II and its TM portion gets cleaved. 2c. It is now a cytoplasmic protein that can travel to the nucleus and increase expression of proteins that relieve the unfolded crisis. 4. If these mechanisms don't work, then RER transports protiens to the pore they originally came from into the cytoplasm, where they are degraded. |
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Where does glycosaminoglycan synthesis occur?
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Trans Golgi
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What are some of the functions of endocytosis?
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1. to replenish PM
2. internalizing protein receptors 3. maintains surface area of cell 4. brings in different concentrations of salts and proteins from ECM 5. mode of entry into cells of numerous toxins and viruses |
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Describe how LDL gets into a cell.
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1. LDL binds LDL receptor on PM.
2. Induces coat formation. 3. Coated vesicle fuses with early endosome. 4. Low pH of endosome causes receptor to dissociate and return to PM. 5. LDL is degraded later on to free cholesterol. |
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Name 3 examples of diseases that involve endocytosis.
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1. Listeria Monocytogenes
2. Epstein Barr Virus 3. Vesicular Stomatitis Virus |
