2Z5J: Free Transportin 1

Transportin 1 (Trn1) is a transport receptor that transports substrates from the cytoplasm to the nucleus through nuclear pore complexes by recognizing nuclear localization signals (NLSs). Here we describe four crystal structures of human Trn1 in a substrate-free form as well as in the complex with three NLSs (hnRNP D, JKTBP, and TAP, respectively). Our data have revealed that (1) Trn1 has two sites for binding NLSs, one with high affinity (site A) and one with low affinity (site B), and NLS interaction at site B controls overall binding affinity for Trn1; (2) Trn1 recognizes the NLSs at site A followed by conformational change at site B to interact with the NLSs; and (3) a long flexible loop, characteristic of Trn1, interacts with site B, thereby displacing transport substrate in the nucleus. These studies provide deep understanding of substrate recognition and dissociation by Trn1 in import pathways.
PDB ID: 2Z5JDownload
MMDB ID: 60416
PDB Deposition Date: 2007/7/13
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 3.4  Å
Source Organism:
Similar Structures:
Biological Unit for 2Z5J: monomeric; determined by author
Molecular Components in 2Z5J
Label Count Molecule
Protein (1 molecule)
Transportin-1(Gene symbol: TNPO1)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB