background:
Transportin 1 is the beta subunit of the karyopherin receptor complex which interacts with nuclear localization signals to target proteins to the nucleus. The karyopherin receptor complex is a heterodimer of an alpha subunit which recognizes the nuclear localization signal and a beta subunit which docks the complex at nucleoporins. Alternate splicing of this gene results in two transcript variants encoding different proteins. In cases of HISLV1 infections, transportin 1 is known to bind and mediate the nuclear import of HISLV1 Rev.
Function:
Functions in nuclear protein import as nuclear transport receptor. Serves as receptor for nuclear localization signals (NLS) in cargo substrates. Is thought to mediate docking of the importin/substrate complex to the nuclear pore complex (NPC) through binding to nucleoporin and the complex is subsequently translocated through the pore by an energy requiring, Ran-dependent mechanism. At the nucleoplasmic side of the NPC, Ran binds to the importin, the importin/substrate complex dissociates and importin is re-exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran. The directionality of nuclear import is thought to be conferred by an asymmetric distribution of the GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus (By similarity). Involved in nuclear import of M9-containing proteins. In vitro, binds directly to the M9 region of the heterogeneous nuclear ribonucleoproteins (hnRNP), A1 and A2 and mediates their nuclear import. Appears also to be involved in hnRNP A1/A2 nuclear export. Mediates the nuclear import of ribosomal proteins RPL23A, RPS7 and RPL5. Binds to a beta-like import receptor binding (BIB) domain of RPL23A. In vitro, mediates nuclear import of H2A, H2B, H3 and H4 histones, and SRP19. In case of HISLV1 infection, binds and mediates the nuclear import of HISLV1 Rev.
Subunit:
Binds HNRPA1, HNRPA2, HNRPDL, RPL23A, RPS7, RPL5, RAN and SRP19. Interacts with H2A, H2B, H3 and H4 histones. Binds to HISLV1 Rev.
Subcellular Location:
Cytoplasm. Nucleus.
Similarity:
Belongs to the importin beta family.
Contains 8 HEAT repeats.
Contains 1 importin N-terminal domain.
Database links:
UniProtKB/Swiss-Prot: Q92973.2
Entrez Gene: 3842 Human
Entrez Gene: 238799 Mouse
Omim: 602901 Human
SwissProt: Q92973 Human
SwissProt: Q8SFY9 Mouse
Unigene: 482497 Human
Unigene: 173286 Mouse
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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