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In vitro characterization of rice importin β1: molecular interaction with nuclear transport factors and mediation of nuclear protein import
Author(s) -
Jiang Chang-Jie,
Imamoto Naoko,
Matsuki Rikyu,
Yoneda Yoshihiro,
Yamamoto Naoki
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01207-1
Subject(s) - importin , nuclear transport , nuclear localization sequence , nls , microbiology and biotechnology , biology , ran , chemistry , biochemistry , cell nucleus , nucleus
We recently isolated two cDNAs encoding importin β homologues (rice importin β1 and β2), the first such homologues identified in plants. To address the function of rice importin β1 in the process of nuclear import of proteins, we carried out in vitro binding and nuclear import assays. Recombinant protein of rice importin β1 assembled a complex (PTAC) with rice importin α1 and NLS protein, and also bound to the nuclear envelope of tobacco BY‐2 cells. Ran‐GTP, but not Ran‐GDP, interacted with rice importin β1 and dissociated the heterodimer formed between rice importin α1 and rice importin β1. An in vitro nuclear import assay using digitonin‐permeabilized HeLa cells revealed that rice importin β1 can mediate nuclear envelope docking of NLS proteins and their subsequent translocation into the nucleus. These data strongly suggest that rice importin β1 functions as a component of the NLS receptor in plant cells.