Protein transport into the endoplasmic reticulum (er) or mitochondria requires unfolding of the protein and threading the amino acid chain through a channel or pore into the organelle. in contrast, protein transport into the nucleus does not require unfolding of the protein. why is unfolding unnecessary for nuclear protein import?

The nuclear pore complex is a huge structure composed of about 30 different pore proteins, and its central channel has a diameter of approximately 10-40 nm, which is large enough for even very large protein complexes. For this reason, it is unnecessary to unfold the protein, which can pass through the pore in its native state.

Explanation:

Protein transport into the endoplasmic reticulum (ER) or mitochondria requires unfolding of the protein and threading the amino acid chain through a channel or pore into the organelle. In contrast, protein transport into the nucleus does not require unfolding of the protein.This is because, nuclear pore complex is a huge structure composed of about 30 different pore proteins, and its central channel has a diameter of approximately 10-40 nm, which is large enough for even very large protein complexes. For this reason, it is unnecessary to unfold the protein, which can pass through the pore in its native state.