Final answer:
During protein export from the nucleus, the cargo exhibits a nuclear export signal.
Step-by-step explanation:
During protein export from the nucleus, the cargo exhibits a nuclear export signal. This signal is recognized by specific nuclear transport receptors, which help in the transportation of the cargo through the nuclear pores into the cytoplasm. These nuclear export signals can be found in the cargo proteins themselves or can be attached to the cargo in the form of specific nucleotide sequences.
For example, in the case of mRNA export from the nucleus, specialized proteins mark the mature mRNA for export. These proteins include a nuclear transport receptor, a poly-A-binding protein, and a protein that binds the methyl guanosine cap. These interactions facilitate the transport of the mRNA through nuclear pores into the cytoplasm.
Overall, the cargo exhibits nuclear export signals that aid in the export of proteins, including mRNA, from the nucleus.