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- Title
Human cyclin B3.
- Authors
Tschöp, Katrin; Müller, Gerd A.; Grosche, Jens; Engeland, Kurt
- Abstract
Cyclins form complexes with cyclin-dependent kinases. By controlling activity of the enzymes, cyclins regulate progression through the cell cycle. A- and B-type cyclins were discovered due to their distinct appearance in S and G2 phases and their rapid proteolytic destruction during mitosis. Transition from G2 to mitosis is basically controlled by B-type cyclins. In mammals, two cyclin B proteins are well characterized, cyclin B1 and cyclin B2. Recently, a human cyclin B3 gene was described. In contrast to the expression pattern of other B-type cyclins, we find cyclin B3 mRNA expressed not only in S and G2/M cells but also in G0 and G1. Human cyclin B3 is expressed in different variants. We show that one isoform remains in the cytoplasm, whereas the other variant is translocated to the nucleus. Transport to the nucleus is dependent on three autonomous nonclassical nuclear localization signals that where previously not implicated in nuclear translocation. It had been shown that cyclin B3 coimmunoprecipitates with cdk2; but this complex does not exhibit any kinase activity. Furthermore, a degradation-resistant version of cyclin B3 can arrest cells in G1 and G2. Taken together with the finding that cyclin B3 mRNA is not only expressed in G2/M but is also detected in significant amounts in resting cells and in G1 cells. This may suggest a dominant-negative function of human cyclin B3 in competition with activating cyclins in G0 and the G1 phase of the cell cycle.
- Subjects
CYCLINS; CYCLIN-dependent kinases; CELL cycle; CYTOPLASM; MESSENGER RNA
- Publication
FEBS Journal, 2006, Vol 273, Issue 8, p1681
- ISSN
1742-464X
- Publication type
Article
- DOI
10.1111/j.1742-4658.2006.05184.x