Which step happens after cargo binding in the nuclear import process?

In the nuclear import process, after the cargo binds to its specific receptor in the cytoplasm, the next critical step involves the movement of the receptor-cargo complex to the nucleus. This is facilitated by interactions with the nuclear pore complex, which acts as a gateway between the cytoplasm and the nucleus.

Once at the nuclear pore, the receptor-cargo complex undergoes a series of conformational changes that allow it to be transported through the pore and into the nucleus. The nuclear import process is highly regulated and relies on specific signals, such as nuclear localization signals (NLS) present on the cargo, which are recognized by the importin receptors.

Moving cargo to the mitochondria or binding it to the cytoskeleton are not steps involved in nuclear import and do not occur in this context. Additionally, the cargo is not released into the cytosol; rather, it is released within the nucleus after the import process is complete, where it can then perform its specific functions. Therefore, the correct answer reflects the critical step of transporting the receptor-cargo complex into the nucleus after cargo binding.