Importazole #10451

Importazole is a cell-permeable, specific inhibitor of importin-β-mediated nuclear import (1). Nuclear import through importin β1 association with adaptor importin α is an essential component of the classical nuclear localization signal (NLS) pathway. Following recognition of the cargo target NLS by importin α, the cargo:importin α:importin β1 complex is transported across the nuclear pore complex into the nucleus, where it dissociates by binding the small, GTP-bound GTPase Ran (2). Importazole blocks importin-β-mediated nuclear import by specifically inhibiting importin-β function, likely through altering the interaction between RanGTP and importin-β (1). Inhibition of the RanGTP/importin-β pathway by Importazole in mitotic cells results in multiple mitotic defects, including defects in spindle assembly, chromosome congression, and spindle centering (3). Similar results were seen in mouse oocytes, where Importazole treatment blocks meiosis I (MI) spindle formation and function (4).