KPNA2/Karyopherin α2 [B9]

KPNA2 (Karyopherin α2), a member of the importin alpha family, contains an N-terminal importin beta binding (IBB) motif followed by a hydrophobic region consisting of 10 armadillo repeats that function in binding to the nuclear localization signal (NLS) sites of cargo proteins. Two cytosolic factors centrally involved in the recognition and docking process are the karyopherin α1 and karyopherin β1 subunits. Karyopherin α1 functions in the recognition and targeting of substrates destined for nuclear import, while karyopherin β1 serves as an adapter, tethering the karyopherin α1/substrate complex to docking proteins on the nuclear envelope termed nucleoporins. KPNA2 has been shown to complex with Epstein-Barr virus nuclear antigen 1 (EBNA1). Certain RNA-binding proteins are imported to the nucleus by karyopherin β2, and karyopherin β3 appears to be involved in the import of some ribosomal proteins. Research studies indicate that KPNA2 promotes cell proliferation and tumorigenesis. Research studies have also shown that up-regulation of KPNA2 is associated with cancer progression. Therefore, it has become a focus of biomarker research.