TNPO1
Description
The TNPO1 (transportin 1) is a protein-coding gene located on chromosome 5.
TNPO1 is a protein that functions as a karyopherin, mediating the transport of proteins into the nucleus. It binds to nuclear localization signals on cargo proteins and may not require an importin alpha subunit to do so. TNPO1 uses a similar mechanism to other importins, docking to the nuclear pore complex and being translocated through the pore by an energy-requiring process. Ran protein binds to TNPO1 in the nucleus, causing it to dissociate from its cargo, and TNPO1 is then re-exported to the cytoplasm. TNPO1 also plays a role in transporting proteins into the primary cilium, similar to its function in nuclear transport.
TNPO1 acts as a nuclear transport receptor, facilitating the import of proteins into the nucleus. It binds to nuclear localization signals (NLS) on cargo substrates and mediates their docking to the nuclear pore complex (NPC). This process is energy-dependent and requires the involvement of Ran, a GTPase protein. Once inside the nucleus, the complex dissociates and TNPO1 is re-exported to the cytoplasm. TNPO1 is involved in the import of various proteins, including those containing the M9 region, such as heterogeneous nuclear ribonucleoproteins (hnRNPs) A1 and A2, ribosomal proteins RPL23A, RPS7, and RPL5, histones H2A, H2B, H3, and H4, SRP19, and isoforms 1 and 5 of ADAR/ADAR1.
TNPO1 is also known as IPO2, KPNB2, MIP, MIP1, TRN.
