In eukaryotes, ribosomes (approximate mass 4 × 106 D) are assembled inside the nucleus, which is enclosed by a double membrane. Protein synthesis occurs in the cytosol.
(a) Could a protein similar to a porin or the glucose transporter be responsible for transporting ribosomes into the cytoplasm? Explain.
(b) Would free energy be required to move a ribosome from the nucleus to the cytoplasm? Why or why not?