Question

Using genetic engineering, a student has fused an NES to a protein whose nuclear localization leads to cell lysis but is harmless when in the cytosol. This student has also fused an NLS to another protein that is required in the cytosol for cell viability but is inactive when in nucleus. Whereas wild-type cells die upon the expression of these fusion proteins, she has been able to identify viable mutants, which have a loss-of-function mutation in a gene encoding a protein involved in nucleocytoplasmic transport. The products of these genes are probably ...

A. importins.

B. exportins.

C. either importins or exportins.

D. neither importins nor exportins.

E. involved in the transport of proteins to the extracellular space.

Answer 1

Option A , exportin

As it has been told that a protein whose nuclear localization leads to cell death . To prevent this , student fused to NES ( nucleus exit signal) which help in localizing protein in to cytosol thus prevent cell death. During transport of protein out of the nucleus, a group of protein help known as exportin. They bind with NES and ran protein and help in exit of protein from nucleus to cytosol. Here due to loss of function of exportin protein containg NES can not transported out side. So this protein remain inside and cause cell lysis.