Cyclin F regulates the nuclear localization of cyclin B1 through a cyclin-cyclin interaction.

The key regulator of G(2)-M transition of the cell cycle is M-phase promoting factor (MPF), a complex composed of cdc2 and a B-type cyclin. Cyclin B1 nuclear localization involves phosphorylation within a region called the cytoplasmic retention signal, which also contains a nuclear export signal. The mechanism of MPF nuclear ...
localization remains unclear since it contains no functional nuclear localization signal (NLS). We exploited the yeast two-hybrid screen to find protein(s) potentially mediating localization of cyclin B1 and identified a novel interaction between cyclin B1 and cyclin F. We found that cdc2, cyclin B1 and cyclin F form a complex that exhibits histone H1 kinase activity. Cyclin B1 and cyclin F also colocalize through immunofluorescence studies. Additionally, deletion analysis revealed that each putative NLS of cyclin F is functional. Taken together, the data suggest that the NLS regions of cyclin F regulate cyclin B1 localization to the nucleus. The interaction between cyclin B1 and cyclin F represents the first example of direct cyclin-cyclin binding, and elucidates a novel mechanism that regulates MPF localization and function.
Mesh Terms:
Animals, Biological Transport, CDC2 Protein Kinase, Cell Line, Cell Nucleus, Cyclin B, Cyclin B1, Cyclins, Cytoplasm, Fluorescent Antibody Technique, Humans, Meiosis, Models, Biological, Myristic Acid, Nuclear Localization Signals, Oocytes, Precipitin Tests, Protein Binding, Protein Kinases, RNA, Messenger, Recombinant Fusion Proteins, Sequence Deletion, Two-Hybrid System Techniques, Xenopus laevis
EMBO J.
Date: Mar. 15, 2000
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