1. You hypothesize that the CF cell has defective chloride efflux because the mutation codes for a CFTR protein that is missing a 20,000 dalton domain that is required for proper CFTR integration into the plasma membrane. Therefore, a smaller, non-functional version of the CFTR protein accumulates in the cytoplasm of CF cells. In order to test your hypothesis you begin by analyzing a total protein extract of both cell types by SDS-PAGE. a. Sketch in and label the banding pattern you would expect to obtain if your hypothesis is correct. Total protein extract of normal cells will yield 3 separate bands when the gel is stained with Coomassie Blue. CFRT will be near the top (210 kd), the lipid anchored protein will be near the middle (95 kd), the peripheral protein near the bottom (25 kd). Total protein extract of CF cells will give the same pattern except the truncated CFTR protein will have a relative mobility corresponding to ~ 190 kd. b.
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