KPNA1
Description
The KPNA1 (karyopherin subunit alpha 1) is a protein-coding gene located on chromosome 3.
Importin subunit alpha-5 is a protein that in humans is encoded by the KPNA1 gene. Importin subunit alpha-5 has been shown to interact with KPNB1 and UBR5.
KPNA1, also known as Importin subunit alpha-5, plays a crucial role in nuclear protein import. It acts as an adapter protein for the nuclear receptor KPNB1, facilitating the transport of proteins into the nucleus. KPNA1 specifically binds to substrates containing either a simple or bipartite NLS motif, enabling the recognition and import of various proteins. The importin/substrate complex, mediated by KPNB1, docks to the nuclear pore complex (NPC) through interactions with nucleoporin FxFG repeats. This complex is then translocated through the NPC via an energy-dependent, Ran-mediated mechanism. At the nucleoplasmic side of the NPC, Ran binds to importin-beta, leading to the dissociation of the complex. Subsequently, importin-alpha and -beta are re-exported back to the cytoplasm, where GTP hydrolysis releases Ran from importin. The directionality of nuclear import is attributed to the asymmetric distribution of GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus.
KPNA1 is also known as IPOA5, NPI-1, RCH2, SRP1.
