How does the endomembrane system work together with the ribosomes

Question

matt101 · Answer

The endomembrane system refers to the membranes of organelles in the cytoplasm. Since we're talking about ribosomes, the membranes we're concerned about are the outer nuclear membrane and the rough endoplasmic reticulum (which by the way are continuous with one another).

These particular membranes are covered in pores that ribosomes can attach to, so that when the ribosome starts producing a protein, the polypeptide change is actually fed through these pores and into the organelle. This is important for proteins that will either be exocytosed or be trafficked to the plasma membrane, as well as for transcription factors, DNA replicating machinery, etc inside the nucleus.