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BACKGROUND Mitosis is regulated by MPF (maturation promoting factor), the active form of Cdc2/28-cyclin B complexes. Increasing levels of cyclin B abundance and the loss of inhibitory phosphates from Cdc2/28 drives cells into mitosis, whereas cyclin B destruction inactivates MPF and drives cells out of mitosis. Cells with defective spindles are arrested in(More)
BACKGROUND Direct synthesis of genes is rapidly becoming the most efficient way to make functional genetic constructs and enables applications such as codon optimization, RNAi resistant genes and protein engineering. Here we introduce a software tool that drastically facilitates the design of synthetic genes. RESULTS Gene Designer is a stand-alone(More)
Like early Xenopus embryos, extracts made from Xenopus eggs lack the cell cycle checkpoint that keeps anaphase from occurring before spindle assembly is complete. At very high densities of sperm nuclei, however, microtubule depolymerization arrests the extracts in mitosis. The arrested extracts have high levels of maturation-promoting factor activity, fail(More)
The spindle assembly checkpoint (SAC) is required to block sister chromatid separation until all chromosomes are properly attached to the mitotic apparatus. The SAC prevents cells from entering anaphase by inhibiting the ubiquitylation of cyclin B1 and securin by the anaphase promoting complex/cyclosome (APC/C) ubiquitin ligase. The target of the SAC is the(More)
We have developed a functional screen in yeast to identify ligands for receptor tyrosine kinases. Using this method, we cloned two Xenopus genes that activate the fibroblast growth factor (FGF) receptor. These encode novel secreted proteins, designated FRL1 and FRL2, distantly related to the epidermal growth factor and angiogenin/ribonuclease families,(More)
BACKGROUND Production of proteins as therapeutic agents, research reagents and molecular tools frequently depends on expression in heterologous hosts. Synthetic genes are increasingly used for protein production because sequence information is easier to obtain than the corresponding physical DNA. Protein-coding sequences are commonly re-designed to enhance(More)
The cyclins are a family of proteins encoded by maternal mRNA. Cyclin polypeptides accumulate during interphase and are destroyed during mitosis at about the time of entry into anaphase. We show here that Xenopus oocytes contain mRNAs encoding two cyclins that are major translation products in a cell-free extract from activated eggs. Cutting these mRNAs(More)
Highly purified maturation-promoting factor (MPF) from Xenopus eggs contains both cyclin B1 and cyclin B2 as shown by Western blotting and immunoprecipitation using Xenopus anti-B-type cyclin antibodies. Immunoprecipitates with these antibodies display the histone H1 kinase activity characteristic of MPF, for which exogenously added B1 and B2 cyclins are(More)
DNA sequences are now far more readily available in silico than as physical DNA. De novo gene synthesis is an increasingly cost-effective method for building genetic constructs, and effectively removes the constraint of basing constructs on extant sequences. This allows scientists and engineers to experimentally test their hypotheses relating sequence to(More)
We have measured the levels of cyclin mRNAs and polypeptides during oogenesis, progesterone-induced oocyte maturation, and immediately after egg activation in the frog, Xenopus laevis. The mRNA for each cyclin is present at a constant level of approximately 5 x 10(7) molecules per oocyte from the earliest stages of oogenesis until after fertilization. The(More)