Importin alpha 2/KPNA2: ProductsKPNA2 (Karyopherin subunit alpha 2; also SRP1a, Importin subunit a2 and RAG1) is a 58-60 kDa member of the Importin alpha family of proteins. It is ubiquitously expressed, and found in both nucleus and cytoplasm. KPNA2 functions as a cargo carrier that transports various complexes from cytoplasm into nucleus. For the MRN DNA repair complex, KPNA2 first binds to NBS1, and then to Importin b1, which mediates movement through the nuclear pore. Human KPNA2 is 529 amino acids (aa) in length. It contains an N-terminal IBB/Importin b domain (aa 2-60), ten Armadillo repeats that bind "cargo" (aa 71-496) and two intervening NLS binding sites. There is one splice variant that shows a deletion of aa 72-310, coupled to an 11 aa substitution for aa 389-406. Over aa 1-132, human KPNA2 shares 94% aa identity with mouse KPNA2.