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Nuclear localization signal and protein context both mediate importin α specificity of nuclear import substrates

Item Type:Article
Title:Nuclear localization signal and protein context both mediate importin α specificity of nuclear import substrates
Creators Name:Friedrich, B. and Quensel, C. and Sommer, T. and Hartmann, E. and Koehler, M.
Abstract:The 'classical' nuclear protein import pathway depends on importin alpha and importin beta. Importin alpha binds nuclear localization signal (NLS)-bearing proteins and functions as an adapter to access the importin beta dependent import pathway. In humans only one importin beta is known to interact with importin alpha, while six alpha importins have been described. Various experimental approaches provided evidence that several substrates are transported specifically by particular alpha importins. Whether or not the NLS is sufficient to mediate importin alpha specificity is unclear. To address this question, we exchanged the NLS of two well-characterized import substrates, the seven-bladed propeller protein RCC1, preferentially transported into the nucleus by importin alpha3, and the less specifically imported substrate nucleoplasmin. In vitro binding studies and nuclear import assays revealed that both NLS and protein context contribute to specificity of importin alpha binding and transport.
Keywords:Cell Nucleus Active Transport, Biological Transport, Cell Cycle Proteins, Cell Nucleus, Escherichia coli, Glutathione Transferase, Guanine Nucleotide Exchange Factors, Hela Cells, Nuclear Localization Signals, Nuclear Proteins, Phosphoproteins, Proteins, Recombinant Fusion Proteins, Substrate Specificity, alpha Karyopherins
Source:Molecular and Cellular Biology
ISSN:0270-7306
Publisher:American Society for Microbiology (U.S.A.)
Volume:26
Number:23
Page Range:8697-8709
Date:December 2006
Official Publication:https://doi.org/10.1128/MCB.00708-06
PubMed:View item in PubMed

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