Subunits of the Heterotrimeric Transcription Factor NF-Y Are Imported into the Nucleus by Distinct Pathways Involving Importin β and Importin 13
| Autor: | Werner Albig, Joerg Kahle, Matthias Baake, Detlef Doenecke |
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| Rok vydání: | 2005 |
| Předmět: |
Microinjections
Recombinant Fusion Proteins Protein subunit Amino Acid Motifs Molecular Sequence Data Gene Expression Importin Karyopherins Biology Binding Competitive Xenopus laevis 03 medical and health sciences 0302 clinical medicine Heterotrimeric G protein medicine Animals Humans Amino Acid Sequence Molecular Biology Conserved Sequence Glutathione Transferase 030304 developmental biology Cell Nucleus 0303 health sciences Sequence Homology Amino Acid Cell Biology beta Karyopherins Protein Subunits Cell nucleus medicine.anatomical_structure CCAAT-Binding Factor Biochemistry 030220 oncology & carcinogenesis Histone fold Mutagenesis Site-Directed Oocytes Female Beta Karyopherins Nuclear transport Dimerization Nuclear localization sequence HeLa Cells Protein Binding |
| Zdroj: | Molecular and Cellular Biology. 25:5339-5354 |
| ISSN: | 1098-5549 |
| Popis: | The transcriptional activator NF-Y is a heterotrimeric complex composed of NF-YA, NF-YB, and NF-YC, which specifically binds the CCAAT consensus present in about 30% of eukaryotic promoters. All three subunits contain evolutionarily conserved core regions, which comprise a histone fold motif (HFM) in the case of NF-YB and NF-YC. Our results of in vitro binding studies and nuclear import assays reveal two different transport mechanisms for NF-Y subunits. While NF-YA is imported by an importin beta-mediated pathway, the NF-YB/NF-YC heterodimer is translocated into the nucleus in an importin 13-dependent manner. We define a nonclassical nuclear localization signal (ncNLS) in NF-YA, and mutational analysis indicates that positively charged amino acid residues in the ncNLS are required for nuclear targeting of NF-YA. Importin beta binding is restricted to the monomeric, uncomplexed NF-YA subunit. In contrast, the nuclear import of NF-YB and NF-YC requires dimer formation. Only the NF-YB/NF-YC dimer, but not the monomeric components, are recognized by importin 13 and are imported into the nucleus. Importin 13 competes with NF-YA for binding to the NF-YB/NF-YC dimer. Our data suggest that a distinct binding platform derived from the HFM of both subunits, NF-YB/NF-YC, mediates those interactions. |
| Databáze: | OpenAIRE |
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