1a.Nucleoplasmin, is a protein
involved in chromatin assembly that is transported to the nucleus.
In an experiment designed to study what part of nucleoplasmin has
the nuclear localization signal, investigators added a red dye
molecule which stained the protein. They then injected the intact
protein or combinations of its subunits into the cytoplasm of a
frog oocyte or into its nucleus.

The results of the experiment
are shown in the diagram, where red indicates the location
of the labeled protein. Based on these results, which part of the
nucleoplasmin protein bears a nuclear localization signal?

1b. Nuclear localization signals are not cleaved off after
transport into the nucleus, whereas signal sequences for the import
into other organelles are often removed after import. Why do you
suppose it is critical that nuclear localization signals remain
attached to their proteins (hint: think about what happens to the
nucleus during mitosis).

1c. As you learned in this module, proteins with nuclear
localization signal are nearly always transported to the nucleus
after translation.