Molecular cloning and functional characterization of mouse Nxf family gene products.
Tap, a member of the evolutionarily conserved nuclear RNA export factor (NXF) family of proteins, has been implicated in the nuclear export of bulk poly(A)+ RNAs. cDNAs encoding the mouse NXF proteins (Tap, NXF7, NXF2, and NXF3) were prepared and the gene products were characterized in terms of their genomic organization, expression patterns, and biochemical properties. Mouse Tap was found to be ubiquitously expressed, whereas tissue- and developmental stage specific expression of mouse Nxf2, Nxf3, and Nxf7 was observed. Although mouse Tap and NXF2 bound to the phenylalanine-glycine repeat sequences of nucleoporins, NXF7 and NXF3 did not. GFP-tagged mouse Tap and NXF2 were localized predominantly in the nucleus. In contrast, GFP-tagged NXF7 and NXF3 were localized exclusively in the cytoplasm. As shown for the human counterpart, disruption of the leucine-rich nuclear export signal or leptomycin B treatment abolishes the cytoplasmic localization of mouse NXF3. p15/NXT1, an essential cofactor for human Tap in the export of mRNAs, was able to bind to mouse Tap, NXF2, and NXF3, but NXF7 did not form a stable heterodimeric complex. Transient transfection experiments indicated that only mouse Tap and NXF2 enhance the nuclear export of an otherwise inefficiently exported mRNA substrate. The orthologous relationship between human and mouse Nxf genes is discussed on the basis of these data.
Sasaki
Mitsuho
M
Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Takeda
Eri
E
Takano
Keizo
K
Yomogida
Kentarou
K
Katahira
Jun
J
Yoneda
Yoshihiro
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli; D040461:Gene Components; D020869:Gene Expression Profiling; D005822:Genetic Vectors / Q000235:genetics; D049452:Green Fluorescent Proteins; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D018076:DNA, Complementary; C568774:NXF3 protein, mouse; D028861:Nuclear Pore Complex Proteins; D029543:Nucleocytoplasmic Transport Proteins; D016601:RNA-Binding Proteins; D049452:Green Fluorescent Proteins; D015500:Chloramphenicol O-Acetyltransferase