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Gene X has a point mutation resulting in a premature stop codon in the mRNA. Ima

ID: 143346 • Letter: G

Question

Gene X has a point mutation resulting in a premature stop codon in the mRNA. Imagine one cell line with this mutant was wild type (for all non Gene X genes) while another had a mutation in the nonsense mediated decay (NMD) pathway in addition to the Gene X mutation. If proteins were extracted from each cell line and a western blot probing for Gene X was performed, what would we expect to see on the western blot?

Choices e and d are incorrect so far

a) The Gene X band from both cell lines will be the same size and intensity.

Explanation / Answer

Option c is what I believe is right. The nonsense proteins are always destructed by a pathway called NMD as those proteins are of no use. According to the given scenario the NMD mutant cell line are incapable of destructing the accumulating nonsense protein from gene X and when blotted will give darker band due to more protein load, where as the gene x has the nonsense proteins being removed and hence the band will be lighter when blotted. Size of protein will be same as both the cell lines has same mutation in gene X at same loci.