KPNA5 encodes karyopherin subunit alpha 5, an importin alpha adapter protein that mediates nuclear protein import by recognizing classical and non-classical nuclear localization signals. It is part of the machinery that carries selected proteins from the cytoplasm to the nucleus and supports signal-dependent nuclear trafficking. Its expression is high in the male reproductive system and is also detected in brain, eye, and renal system tissues. KPNA5 acts with KPNB1 to dock cargo at the nuclear pore and enable Ran-dependent translocation into the nucleus. Through this transport route, it recognizes nuclear localization motifs in transcription factors and viral proteins, including STAT1, STAT2, and influenza nucleoprotein, thereby linking cargo recognition at the cytosol to import across the nuclear pore complex.