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Two separate regions essential for nuclear import of the hnRNP D nucleocytoplasmic shuttling sequence
Author(s) -
Suzuki Maiko,
Iijima Megumi,
Nishimura Akira,
Tomozoe Yusuke,
Kamei Daisuke,
Yamada Michiyuki
Publication year - 2005
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2005.04820.x
Subject(s) - sequence (biology) , nuclear transport , microbiology and biotechnology , computational biology , biology , chemistry , genetics , cell nucleus , nucleus
Heterogeneous nuclear ribonucleoprotein (hnRNP) D/AUF1 functions in mRNA genesis in the nucleus and modulates mRNA decay in the cytoplasm. Although it is primarily nuclear, it shuttles between the nucleus and cytoplasm. We studied the nuclear import and export of the last exon‐encoding sequence common to all its isoforms by its expression as a green fluorescent protein‐fusion protein in HeLa cells and by heterokaryon assay. The C‐terminal 19‐residue sequence (SGYGKVSRRGGHQNSYKPY) was identified as an hnRNP D nucleocytoplasmic shuttling sequence (DNS). In vitro nuclear transport using permeabilized cells indicated that nuclear import of DNS is mediated by transportin‐1 (Trn‐1). DNS accumulation in the nucleus was dependent on Trn‐1, Ran, and energy in multiple rounds of nuclear transport. Use of DNS with deletions, alanine scanning mutagenesis and point mutations revealed that two separate regions (the N‐terminal seven residues and the C‐terminal two residues) are crucial for in vivo and in vitro transport as well as for interaction with Trn‐1. The N‐ and C‐terminal motifs are conserved in the shuttling sequences of hnRNP A1 and JKTBP.