Importin subunit alpha-3 (KPNA4) (KPNA4)

Importin subunit alpha-3 (KPNA4) is a critical adapter protein in the classical nuclear import pathway, belonging to the karyopherin alpha family [3, 15]. It functions by recognizing and binding to nuclear localization signals (NLS) on cytoplasmic cargo proteins, such as the NF-kappaB subunits (p50/p65), IRF3, and c-Fos, and subsequently recruits importin beta-1 to facilitate translocation through the nuclear pore complex [5, 24]. KPNA4 plays a pivotal role in regulating signal transduction, immune responses, and cell cycle progression by controlling the nuclear entry of key transcription factors [2, 23]. In various pathological states, KPNA4 is often dysregulated; it is frequently overexpressed in cancers like prostate and hepatocellular carcinoma, where it promotes metastasis and tumor growth, while its downregulation is associated with psychiatric disorders such as schizophrenia [19, 25, 26]. Additionally, KPNA4 is a major target for viral subversion, as many viruses (e.g., Influenza, HIV, and SARS-CoV-2) utilize or block this pathway to facilitate their replication or evade the host's innate immune response [11, 31]. Therapeutic strategies targeting KPNA4 include small molecule inhibitors like piperine and lactucopicrin, as well as peptidomimetics, which aim to disrupt the interaction between the adapter and its cargo to treat cancer, chronic pain, and infectious diseases [1, 24, 29].

Other names

Karyopherin subunit alpha-4QIP1SRP1-gammaIPOA3Karyopherin alpha-4

Competitive inhibition of the nuclear localization signal (NLS) binding sites (major and minor) on the importin alpha protein [1, 11]. This prevents the formation of the trimeric importin alpha/beta/cargo complex and blocks the translocation of cargo proteins into the nucleus [15, 31].