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In vivo evidence for involvement of a 58 kDa component of nuclear pore‐targeting complex in nuclear protein import.
Author(s) -
Imamoto N.,
Shimamoto T.,
Takao T.,
Tachibana T.,
Kose S.,
Matsubae M.,
Sekimoto T.,
Shimonishi Y.,
Yoneda Y.
Publication year - 1995
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1995.tb00031.x
Subject(s) - importin , nuclear transport , nuclear pore , biology , cytoplasm , nuclear localization sequence , nuclear protein , nls , microbiology and biotechnology , cell nucleus , nucleoporin , biochemistry , gene , transcription factor
We recently showed that a nuclear location signal (NLS)‐containing karyophile forms a stable complex with cytoplasmic components for nuclear pore‐targeting The complex, termed nuclear pore‐targeting complex (PTAC), contained two essential proteins of 54 and 90 kDa, respectively, as estimated by electrophoresis. In this study, we found that the 54 kDa component of PTAC is the mouse homologue of Xenopus importin (m‐importin). Cytoplasmic injection of the antibodies raised against recombinant m‐importin showed an inhibitory effect on nuclear import of a karyophile in living mammalian cells. A portion of cytoplasmically injected antibodies migrated rapidly into the nucleus, indicating dynamic movement of this protein across the nuclear envelope. Moreover, the injected antibodies co‐precipitated the karyophile, in an NLS‐dependent manner, with endogenous m‐importin in the cytoplasm. These results provide in vivo evidence that m‐importin is involved in nuclear protein import through association with a NLS in the cytoplasm before nuclear pore binding.