Final answer:
Cargo proteins are unbound from the import protein in nuclear transport through specific interactions and mechanisms, including ATP hydrolysis and interactions with other proteins.
Step-by-step explanation:
Proteins involved in nuclear transport, known as cargo proteins, become unbound from the import protein through specific interactions and mechanisms. In the process of nuclear transport, nuclear localization signals (NLS) on cargo proteins enable binding to nuclear transport receptor proteins in the cytosol. Once bound, the cargo proteins are transported into the nucleus through nuclear pores. Once inside the nucleus, the cargo proteins are released from the import protein through various mechanisms, including ATP hydrolysis and interactions with other proteins.