Which signal is associated with nuclear export of proteins?

The nuclear export signal is a specific amino acid sequence that is recognized by transport receptors, facilitating the export of proteins from the nucleus to the cytoplasm. Proteins that need to leave the nucleus typically contain this signal, which binds to exportins – proteins that mediate the transport process through the nuclear pore complex. Once the exportin binds the protein with the nuclear export signal, the protein is transported across the nuclear envelope, ensuring that it reaches the cytoplasm where it can perform its functions.

In contrast, a nuclear localization signal is responsible for localizing proteins into the nucleus rather than exporting them. Ribosomal binding signals and signal recognition particle signals are related to protein synthesis and targeting to the endoplasmic reticulum, rather than nuclear trafficking. Therefore, the association of the nuclear export signal with the process of moving proteins out of the nucleus makes it the correct answer in this context.