Mos stimulates MAP kinase in Xenopus oocytes and activates a MAP kinase kinase in vitro
| Autor: | Natalie G. Ahn, N Yew, James Posada, Jonathan A. Cooper, G F Vande Woude |
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| Rok vydání: | 1993 |
| Předmět: |
musculoskeletal diseases
endocrine system Microinjections MAPK7 Mitosis Mitogen-activated protein kinase kinase MAP2K7 Xenopus laevis Animals c-Raf Phosphorylation Molecular Biology reproductive and urinary physiology MAPK14 biology MAP kinase kinase kinase urogenital system Cyclin-dependent kinase 2 Cell Biology Phosphoproteins Enzyme Activation Biochemistry Calcium-Calmodulin-Dependent Protein Kinases Proto-Oncogene Proteins c-mos embryonic structures Oocytes biology.protein Cyclin-dependent kinase 9 Protein Kinases Research Article |
| Zdroj: | Molecular and Cellular Biology. 13:2546-2553 |
| ISSN: | 1098-5549 0270-7306 |
| DOI: | 10.1128/mcb.13.4.2546 |
| Popis: | Several protein kinases, including Mos, maturation-promoting factor (MPF), mitogen-activated protein (MAP) kinase, and MAP kinase kinase (MAPKK), are activated when Xenopus oocytes enter meiosis. De novo synthesis of the Mos protein is required for progesterone-induced meiotic maturation. Recently, bacterially synthesized maltose-binding protein (MBP)-Mos fusion protein was shown to be sufficient to initiate meiosis I and MPF activation in fully grown oocytes in the absence of protein synthesis. Here we show that MAP kinase is rapidly phosphorylated and activated following injection of wild-type, but not kinase-inactive mutant, MBP-Mos into fully grown oocytes. MAP kinase activation by MBP-Mos occurs within 20 min, much more rapidly than in progesterone-treated oocytes. The MBP-Mos fusion protein also activates MPF, but MPF activation does not occur until approximately 2 h after injection. Extracts from oocytes injected with wild-type but not kinase-inactive MBP-Mos contain an activity that can phosphorylate MAP kinase, suggesting that Mos directly or indirectly activates a MAPKK. Furthermore, activated MBP-Mos fusion protein is able to phosphorylate and activate a purified, phosphatase-treated, rabbit muscle MAPKK in vitro. Thus, in oocytes, Mos is an upstream activator of MAP kinase which may function through direct phosphorylation of MAPKK. |
| Databáze: | OpenAIRE |
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