Question

You have isolated a new nuclear protein, whose expression level is signficantly increased in cancer. Careful sequence analysis reveals the following sequence in the N-terminus of this protein (the positions of the amino acids are indicated): Pro(1)-Pro(2)-Val (3)-Ala(4)-Arg(5)-Lys(6)-Lys(7)-Arg(8)-Lys(9)-Lys(10)-Lys(11)-Tyr(12)-Ile(13)
. A construct in which amino acids 1-10 are deleted does not localize to the nucleus. However, when you fuse amino acids 1-10 to GFP, GFP remains in the cytosol.

Which of the following statements best describes the conclusion that you would draw from this experiment?

a)amino acids 1-10 are necessary but not sufficient to direct the protein's import into the nucleus

b)amino acids 1-10 are necessary and sufficient to target the protein into the nucleus

c)deletion of amino acids 1-10 disrupt the import of all proteins into the nucleus

d)amino acids 1-10 are sufficient for the nuclear import of this protein

e)amino acids 1-10 are critical for nuclear import because they interact with the Ran GTPase

Answer 1

Given that upon the deletion of 1-10 amino acid block the transport of the protein to the nucleus. This means that 1-10 amino acid is necessary for nuclear localization.

When this 10 amino acid long peptide is fused with the GFP, GFP was unable to enter the nucleus. This shows that although peptide is necessary for nuclear localization apart from this there are some other specific sequences which are required for nuclear localization.

So option A is correct. a)amino acids 1-10 are necessary but not sufficient to direct the protein's import into the nucleus