Final answer:
Nuclear import receptors are the proteins that bind to nuclear localization signals on new proteins, guiding them through the nuclear pore complex into the nucleus.
Step-by-step explanation:
The proteins that bind to nuclear localization signals (NLS) on newly synthesized proteins are nuclear import receptors. When a protein contains a nuclear localization signal, which typically consists of a sequence of positively charged amino acids such as lysine and arginine, it is recognized by nuclear import receptors in the cytosol. These receptors are responsible for escorting the protein through the nuclear pore complex into the nucleus, where the protein will function. This process requires energy, which is derived from ATP hydrolysis.