Mechanism of nuclear import:
NLS on a cargo protein binds to a nuclear import receptor, Inducing change in the receptor, causing interaction with the F – G nuclear Porins. Entry into nucleus. RAN in the nucleus, when bound to GTP, has a higher affinity for the nuclear import receptor than NLS. RAN GTP attaches Two new site, releasing cargo proteins from old; receptor conforms and exits. In the cytosol, RAN GAP hydrolyzes RAN GTP to GDP, Releasing RAN from the receptor. Then renters and RAN – GEF (Attached to chromatin) exchanges that RAN GDP for GTP again.