Which proteins bind to nuclear localization signals (NLS) on newly synthesized proteins to facilitate their transport into the nucleus?

Differentiate importins from other proteins: Ubiquitin ligases are involved in tagging proteins for degradation, exportins are responsible for transporting molecules out of the nucleus, and chaperonins assist in protein folding. None of these directly bind to NLS for nuclear import.

Understand the transport process: Once importins bind to the NLS on a protein, they guide the protein through the nuclear pore complex. This process is energy-dependent and often involves interactions with Ran, a small GTPase.