Question 2-4 (29pts). Endomembrane System Let’s compare and contrast these two proteins as they are created and targeted

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Question 2-4 (29pts). Endomembrane System Let’s compare andcontrast these two proteins as they are created and targeted tospecific areas of the cell via vesicular trafficking.
a. ER entry a. Compare and contrast entry into the ER of the LowDensity Lipoprotein Receptor (LDLR) and a lysosomal hydrolase(Cathepsin). In other words, explain signal hypothesis andhighlight similarities and differences in how each protein isprocessed. Rubric (7): Compare and Contrast correctly:Zipcode(s)(1); helper proteins(1), receptors(1), channels(1),enzymes(1), final location after entry (1); ER specificmodifications and where they would be (1).
b. ERGolgi Both proteins need to travel from the ER to theGolgi. Compare and contrast how each protein is selected andtrafficked to the Golgi. Rubric (6): vesicle formation: cargorecognition (1), helper proteins(1), result of pinch-off (1);transport (1); docking-fusion (1), overall explanation is logical(1).
c. Endocytosis: Both proteins can be trafficked to the cellsurface AND both can be endocytosed. Based on the physical locationof each protein with regard to the lipid bilayer, compare andcontrast how each protein gets trafficked to the lysosome from theplasma membrane (outer membrane of the cell). Rubric (7): vesicleformation: cargo recognition (1), helper proteins(1), result ofpinch-off (1); transport (1); docking-fusion (1), additionalcompartments (1) overall explanation is logical (1).
d. High cell cholesterol is associated with aggressive forms ofprostate cancer. Treatment of prostate cancer patients with statinsis actually therapeutic. Statins inhibit HMG CoA reductase activityand decrease the number of LDLRs on the cell surface (you learnedabout this in your problem set). Use your understanding ofendocytosis and cholesterol biosynthesis regulation to explain whythe effects of statins could decrease cholesterol content ofprostate cancer cells. Rubric (4): How is the effect of fewer LDLRreceptors on the cell surface affecting cholesterol content ofcell? (2). How is effect of the drug on enzyme affecting thecholesterol content of the cell? S(2).
e. Observation: Cancer cells have higher concentrations ofphospholipids in their outer membrane (plasma membrane).
i. Researchers have found that choline kinase alpha activity(enzyme that synthesizes a phospholipid) was increased in cancercells. In what organelle would you expect to find this enzyme?Rubric (1): Correct organelle.
ii. Given the organelle you picked in “i”, explain how newlysynthesized phospholipid is transported to the plasma membrane.Rubric (2): Correct mechanism used to explain how SM gets to plasmamembrane. Highway and vehicle!
iii. Cancer cells typically have less cholesterol and morephospholipid in their cell membranes. This phenotype is alsoassociated with resistance to apoptosis. The FAS death receptor(UNIT 3) is localized to lipid rafts. Using this information toexplain why increased phospholipid and decreased cholesterol couldinhibit the initiation of apoptosis. Rubric (2): Plausible linkbetween increased change in membrane composition, fluidity, andlack of FAS receptor activation.