At least in some species is the number of pores per square unit dependent on the activity of the nucleus. It reflects the exchange rate between nucleus and cytosol. The genetic information is stored in the nucleus. Replication , transcription , RNA processing and ribosome assembly do all happen within the nucleus. The required enzymes are imported from the cytosol.
Import is strictly selective and most of the cytosolic proteins are excluded.
The pore complex is involved in the choice of proteins. Nuclear exports are mainly RNA and ribosomes. Membrane-bound ribosomes are able to synthesize polypeptide chains for export or storage. The binding of ribosome to the membrane induces the temporary opening of a membrane pore through which the new and still unfolded polypeptide chain is synthesized. The tertiary structure forms only after entering the ER cistern.