Cloning and characterization of hSRP1γ, a tissue-specific nuclear transport factor

Maxence V. Nachury, Ursula W. Ryder, Angus I. Lamond, Karsten Weis

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    96 Citations (Scopus)


    Nuclear import of proteins containing a nuclear localization signal (NLS) is dependent on the presence of a cytoplasmic NLS receptor, the GTPase Ran, and p10/NTF2. The NLS receptor is a heterodimeric protein consisting of subunits of approximately 60 and 97 kDa, which have been termed importin α/β, karyopherin α/β, or PTAC 58/97. Members of the 60-kDa/importin α subunit family directly bind to the NLS motif and have been shown to function as adaptors that tether NLS-containing proteins to the p97/importin β subunit and to the downstream transport machinery. Herein we report the identification and characterization of hSRP1γ a human importin α homologue. The hSRP1γ protein is around 45% identical to the two previously identified human importin α homologues hSRP1α/Rch1 and NPI/hSRP1. hSRPIγ can form a complex with importin β and is able to mediate import of a BSA-NLS substrate in an in vitro nuclear import system. Interestingly, hSRP1γ shows a very selective expression pattern and is most abundantly expressed in skeletal muscle, representing more than 1% of the total protein in this tissue. A potential role for hSRP1γ in tissue-specific transport events is discussed.

    Original languageEnglish
    Pages (from-to)582-587
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Issue number2
    Publication statusPublished - 20 Jan 1998

    ASJC Scopus subject areas

    • General


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