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Updated: Mar 19, 2026

Single-Molecule Imaging of Nuclear Transport
Published on: June 9, 2010
Importin α: a key molecule in nuclear transport and non-transport functions
Yoichi Miyamoto1, Kohji Yamada2, Yoshihiro Yoneda3
1Laboratory of Nuclear Transport Dynamics, National Institutes of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan ymiyamoto@nibiohn.go.jp.
Abstract:
Importin α performs the indispensable role of ferrying proteins from the cytoplasm into the nucleus with a transport carrier, importin β1. Mammalian cells from mouse or human contain either six or seven importin α subtypes, respectively, each with a tightly regulated expression. Therefore, the combination of subtype expression in a cell defines distinct signaling pathways to achieve progressive changes in gene expression essential for cellular events, such as differentiation. Recent studies reveal that, in addition to nucleocytoplasmic transport, importin αs also serve non-transport functions. In this review, we first discuss the physiological significance of importin α as a nuclear transport regulator, and then focus on the functional diversities of importin αs based on their specific subcellular and cellular localizations, such as the nucleus and plasma membrane. These findings enrich our knowledge of how importin αs actively contribute to various cellular events.
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