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pEg7, a new Xenopus protein required for mitotic chromosome condensation in egg extracts.

Cubizolles F, Legagneux V, Le Guellec R, Chartrain I, Uzbekov R, Ford C, Le Guellec K - J. Cell Biol. (1998)

Bottom Line: This maternal mRNA encodes a protein, pEg7, whose expression is strongly increased during oocyte maturation.A similar localization of pEg7 is observed when sperm chromatin is allowed to form mitotic chromosomes in cytostatic factor-arrested egg extracts.Biochemical experiments show that pEg7 associates with Xenopus chromosome-associated polypeptides C and E, two components of the 13S condensin.

View Article: PubMed Central - PubMed

Affiliation: Biologie et Génétique du Développement, CNRS UPR 41, Université de Rennes I, Campus de Beaulieu, 35042 Rennes cedex, France.

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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Expression of pEg7. (a) Pattern of the proteins revealed by anti–pEg7 P1 and anti–pEg7 G antibodies. Protein  samples corresponding to one unfertilized egg were separated by  SDS-PAGE and transferred onto nitrocellulose. The blots were  probed with preimmune serums, immune serums, or purified antibodies as indicated. Positions of the molecular weight markers  are indicated at the left. The position of pEg7 is indicated by an  arrow. (b) Tissue expression of pEg7. Protein samples (40 μg)  from each different tissue were separated by SDS-PAGE, transferred to a nitrocellulose filter, and probed with purified anti– pEG7 P1 antibodies. (c) Expression of pEg7 in Xl2 culture cells.  Protein samples corresponding to 1.6 × 105 cells were processed  as described above and probed with purified anti–pEg7 P1 or  anti–pEg7 G antibodies as indicated.
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Figure 2: Expression of pEg7. (a) Pattern of the proteins revealed by anti–pEg7 P1 and anti–pEg7 G antibodies. Protein samples corresponding to one unfertilized egg were separated by SDS-PAGE and transferred onto nitrocellulose. The blots were probed with preimmune serums, immune serums, or purified antibodies as indicated. Positions of the molecular weight markers are indicated at the left. The position of pEg7 is indicated by an arrow. (b) Tissue expression of pEg7. Protein samples (40 μg) from each different tissue were separated by SDS-PAGE, transferred to a nitrocellulose filter, and probed with purified anti– pEG7 P1 antibodies. (c) Expression of pEg7 in Xl2 culture cells. Protein samples corresponding to 1.6 × 105 cells were processed as described above and probed with purified anti–pEg7 P1 or anti–pEg7 G antibodies as indicated.

Mentions: We raised two different polyclonal anti–pEg7 antibodies (P1 and G) against two fusion proteins containing nonoverlapping regions of pEg7. The corresponding P (amino acids 489–710) and G (amino acids 720–960) regions are underlined in Fig. 1 B. Fig. 2 a shows that both serums recognized a band migrating as a 150-kD polypeptide in egg extracts. This is in agreement with the molecular weight calculated from the deduced amino acid sequence. This 150-kD band was not revealed by either preimmune serum. The detection of the 150-kD polypeptide was not affected when the G and P1 antibodies were affinity purified against the corresponding fusion proteins.


pEg7, a new Xenopus protein required for mitotic chromosome condensation in egg extracts.

Cubizolles F, Legagneux V, Le Guellec R, Chartrain I, Uzbekov R, Ford C, Le Guellec K - J. Cell Biol. (1998)

Expression of pEg7. (a) Pattern of the proteins revealed by anti–pEg7 P1 and anti–pEg7 G antibodies. Protein  samples corresponding to one unfertilized egg were separated by  SDS-PAGE and transferred onto nitrocellulose. The blots were  probed with preimmune serums, immune serums, or purified antibodies as indicated. Positions of the molecular weight markers  are indicated at the left. The position of pEg7 is indicated by an  arrow. (b) Tissue expression of pEg7. Protein samples (40 μg)  from each different tissue were separated by SDS-PAGE, transferred to a nitrocellulose filter, and probed with purified anti– pEG7 P1 antibodies. (c) Expression of pEg7 in Xl2 culture cells.  Protein samples corresponding to 1.6 × 105 cells were processed  as described above and probed with purified anti–pEg7 P1 or  anti–pEg7 G antibodies as indicated.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2132990&req=5

Figure 2: Expression of pEg7. (a) Pattern of the proteins revealed by anti–pEg7 P1 and anti–pEg7 G antibodies. Protein samples corresponding to one unfertilized egg were separated by SDS-PAGE and transferred onto nitrocellulose. The blots were probed with preimmune serums, immune serums, or purified antibodies as indicated. Positions of the molecular weight markers are indicated at the left. The position of pEg7 is indicated by an arrow. (b) Tissue expression of pEg7. Protein samples (40 μg) from each different tissue were separated by SDS-PAGE, transferred to a nitrocellulose filter, and probed with purified anti– pEG7 P1 antibodies. (c) Expression of pEg7 in Xl2 culture cells. Protein samples corresponding to 1.6 × 105 cells were processed as described above and probed with purified anti–pEg7 P1 or anti–pEg7 G antibodies as indicated.
Mentions: We raised two different polyclonal anti–pEg7 antibodies (P1 and G) against two fusion proteins containing nonoverlapping regions of pEg7. The corresponding P (amino acids 489–710) and G (amino acids 720–960) regions are underlined in Fig. 1 B. Fig. 2 a shows that both serums recognized a band migrating as a 150-kD polypeptide in egg extracts. This is in agreement with the molecular weight calculated from the deduced amino acid sequence. This 150-kD band was not revealed by either preimmune serum. The detection of the 150-kD polypeptide was not affected when the G and P1 antibodies were affinity purified against the corresponding fusion proteins.

Bottom Line: This maternal mRNA encodes a protein, pEg7, whose expression is strongly increased during oocyte maturation.A similar localization of pEg7 is observed when sperm chromatin is allowed to form mitotic chromosomes in cytostatic factor-arrested egg extracts.Biochemical experiments show that pEg7 associates with Xenopus chromosome-associated polypeptides C and E, two components of the 13S condensin.

View Article: PubMed Central - PubMed

Affiliation: Biologie et Génétique du Développement, CNRS UPR 41, Université de Rennes I, Campus de Beaulieu, 35042 Rennes cedex, France.

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.

Show MeSH
Related in: MedlinePlus