Interaction of Sp1 zinc finger with transport factor in the nuclear localization of transcription factor Sp1.
Transcription factor Sp1 is localized in the nucleus and regulates the expression of many cellular genes, but the nuclear transport mechanism of Sp1 is not well understood. In this study, we revealed that GST-fused Sp1 protein bound to endogenous importin α in HeLa cells via the Sp1 zinc finger domains, which comprise the DNA binding domain of Sp1. It was found that the Sp1 zinc finger domains directly interacted with a wide range of importin α including the armadillo (arm) repeat domain and the C-terminal acidic domain. Furthermore, it turned out that all three zinc fingers of Sp1 are essential for binding to importin α. Taken together, these results suggest that the Sp1 zinc finger domains play an essential role as a NLS and Sp1 can be transported into the nucleus in an importin-dependent manner even though it possesses no classical NLSs.
Department of Medicinal Biotechnology, Institute for Medicinal Research, Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78 Sho-machi, Tokushima 770-8505, Japan. kitoh@ph.tokushima-u.ac.jp
Tatsuo
T
Ito
Haruka
H
Kitamura
Chisana
C
Uwatoko
Makiko
M
Azumano
Kohji
K
Itoh
Jun
J
Kuwahara
D021581:Active Transport, Cell Nucleus; D002467:Cell Nucleus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers; D028901:alpha Karyopherins / Q000378:metabolism
D019913:Nuclear Localization Signals; D016329:Sp1 Transcription Factor; D028901:alpha Karyopherins