Importin α: a key molecule in nuclear transport and non-transport functions

J Biochem. 2016 Aug;160(2):69-75. doi: 10.1093/jb/mvw036. Epub 2016 Jun 11.


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.

Keywords: cellular distribution; importin; multifunction; nuclear localization signal; nuclear transport.

Publication types

  • Review

MeSH terms

  • Active Transport, Cell Nucleus
  • Animals
  • Cell Differentiation / physiology*
  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism*
  • Gene Expression Regulation / physiology*
  • Humans
  • Signal Transduction / physiology*
  • alpha Karyopherins / genetics
  • alpha Karyopherins / metabolism*


  • alpha Karyopherins