Cyclin B1 is a cell cycle protein typically associated with the regulation of cellular division (mitosis). Previous studies in this laboratory involving preimplantation mouse embryos found that cyclin B1, or a cyclin B 1-related protein, were present at both G1 and G2/M phase of the cell cycle. Not only was cyclin Bi detected during G1 phase in this study, it was found to be present in higher concentrations at G1 phase through the first three cell cycles. These findings were unexpected, because most of the literature suggests that cyclin B1 is normally degraded during G1 phase. Using immunoprecipitation and immunoblot techniques, a more detailed study of cyclin B1 expression was inititated. Using two different primary antibodies direct against cyclin B1, a 48.97 kDa protein band, which is believed to be cyclin B1, was detected at both G1 and G2/M phases in 1-cell mouse embryos. Using another antibody directed against Cdk1, the kinase that forms a complex with cyclin B1 in order to direct the G2/M transition, a 37 kDa protein band was also detected at both G1 and G2/M phases in 1-cell mouse embryos. In order to determine whether cyclin B1 was present as a complex with Cdk1, immunoblotting with the anti-Cdk1 antibody. Again, a 37kDa protein band was detected at both G1 and G2/M phases. Finally, in order to determine whether the cyclin B1/Cdk1 complex exists in its active form, histone kinase assays were performed using anti-cyclin B1 immunoprecipitates. Kinase activity was detected in immunoprecipitates collected from G2/M phase 1-cell embryos, but no kinase activity was detected from immunoprecipitates collected from G1 phase 1-cell embryos. These data indicate that cyclin B1 and Cdk1 are present and exist as a complex in both G1 and G2/M phases of 1-cell mouse embryos, although the complex only appears to be active at the G2/M phase. / Department of Biology
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/187824 |
| Date | January 2004 |
| Creators | Dann, Jeremiah J. |
| Contributors | Chatot, Clare L. |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | vi, 75 leaves : ill. ; 28 cm. |
| Source | Virtual Press |
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