please answer B thanks! In preliminary studics (shown bclow) you compare the pro
ID: 255762 • Letter: P
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please answer B thanks!
In preliminary studics (shown bclow) you compare the processing of VSVG in WT cells (left) to that in Palbo cells (right. In pulse-chasc expcriments, you pulsc labecls with S methionine for 5 hours followed by washout of the labeled amino acid (lhe "chase"). You then lyse the cells and mix the membrane Iraction (which includes the ER and Golgi membranes) with cytoplasm. At dilTerent time points over a course of 16 minutes you solubilize the membranc and immunoprecipitatc VSVG with a specific antibody and run the precipitates on a gel followed by cxposur usng Xray film. The results are shown: VSV-infected WT HeLa cells VSV-infected PaBo cells . (membranes +cytoplasm) (membranes cytoplasm) Defect in Protein Immunoprecipitation results:- Unprocessed Processed VSV-G 6 8 10 12 14 16 35 2 46 8 10 12 14 16 35 Time post S Met washout (min) Time post''s Met washout (min) . A. Plcase briefly summarize the results shown above and explain why there is a differencc in the data between WT HeLa cells and PuBo cells. 5 ptExplanation / Answer
B.
The PaBo cells are mutant HeLa cell line with a mutation in the enzyme, mannosidase. Due to their inability to provide the enzyme mannosidase, the VSVG is processed. Accidentally, a membrane fraction of wild-type cells got mixed with the membrane fraction of the SMet labeled VSV infected PaBo cells. The accident resulted in the processing of the VSVG.
Explanation 1. The membrane fraction of the wild-type cells might have served as a source of the enzyme mannosidase that most probably catalyzed VSVG processing.
Explanation .2. The PaBo mutants had leaky expression of the enzyme, mannosidase. Due to the prolonged storage, the mannosidase processed the VSV-G protein (albeit slowly). However, this explanation is not as strong as the first one, since the tubes were stored in ice.
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