pEg7, a New Xenopus Protein Required for Mitotic Chromosome Condensation in Egg Extracts |
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| Authors: | Fabien Cubizolles Vincent Legagneux René Le Guellec Isabelle Chartrain Rustem Uzbekov Chris Ford Katherine Le Guellec |
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| Institution: | *Biologie et Génétique du Développement, CNRS UPR 41, Université de Rennes I, Campus de Beaulieu, 35042 Rennes cedex, France; ‡Cell Cycle Group, Laboratory of Electron Microscopy, A.N. Belozersky Institute, Moscow State University, 119899, Moscow, Russia; and §Department of Genetics and Development, School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom |
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| Abstract: | We have isolated a cDNA, Eg7, corresponding to a Xenopus maternal mRNA, which is polyadenylated in mature oocytes and deadenylated in early embryos. This maternal mRNA encodes a protein, pEg7, whose expression is strongly increased during oocyte maturation. The tissue and cell expression pattern of pEg7 indicates that this protein is only readily detected in cultured cells and germ cells. Immunolocalization in Xenopus cultured cells indicates that pEg7 concentrates onto chromosomes during mitosis. A similar localization of pEg7 is observed when sperm chromatin is allowed to form mitotic chromosomes in cytostatic factor-arrested egg extracts. Incubating these extracts with antibodies directed against two distinct parts of pEg7 provokes a strong inhibition of the condensation and resolution of mitotic chromosomes. Biochemical experiments show that pEg7 associates with Xenopus chromosome-associated polypeptides C and E, two components of the 13S condensin. |
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| Keywords: | chromatin condensation mitotic chromosomes Xenopus laevis egg extracts chromosome-associated proteins |
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