pEg7, a New Xenopus Protein Required for Mitotic Chromosome Condensation in Egg Extracts

• Published in: The Journal of cell biology Vol. 143; no. 6; pp. 1437 - 1446
• Main Authors: Cubizolles, Fabien, Legagneux, Vincent, Le Guellec, René, Chartrain, Isabelle, Uzbekov, Rustem, Ford, Chris, Le Guellec, Katherine
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 14.12.1998; The Rockefeller University Press
• Subjects: Adenosine Triphosphatases; Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - metabolism; Amino Acid Sequence; Animals; Antibodies; Biochemistry, Molecular Biology; Cell cycle; Cell Cycle Proteins; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cells, Cultured; Cellular biology; Chromatin; Chromosomes; Chromosomes - physiology; Cloning, Molecular; Complementary DNA; Condensation; DNA; DNA-Binding Proteins; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - metabolism; Egg Proteins; Egg Proteins - chemistry; Egg Proteins - genetics; Egg Proteins - metabolism; Eggs; Female; Freshwater; Gene Expression Regulation; Genomics; Life Sciences; Male; Mitosis; Molecular Sequence Data; Multiprotein Complexes; Oocytes; Oocytes - cytology; Oocytes - physiology; Open Reading Frames; Organ Specificity; Ova; Proteins; Recombinant Proteins; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Tissue Extracts; Tissue Extracts - metabolism; Xenopus; Xenopus Proteins
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.143.6.1437

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.