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© The Rockefeller University Press,
0021-9525/1998//283 $5.00
The Journal of Cell Biology, Volume 140, Number 2,
, 1998 283-293
Article |
A Presumptive Developmental Role for a Sea Urchin Cyclin B Splice Variant

Institut de Génétique Moléculaire, BP 5051, F 34033 Montpellier Cedex France
We show that a splice variant–derived cyclin B is produced in sea urchin oocytes and embryos. This splice variant protein lacks highly conserved sequences in the COOH terminus of the protein. It is found strikingly abundant in growing oocytes and cells committed to differentiation during embryogenesis. Cyclin B splice variant (CBsv) protein associates weakly in the cell with Xenopus cdc2 and with budding yeast CDC28p. In contrast to classical cyclin B, CBsv very poorly complements a triple CLN deletion in budding yeast, and its microinjection prevents an initial step in MPF activation, leading to an important delay in oocyte meiosis reinitiation. CBsv microinjection in fertilized eggs induces cell cycle delay and abnormal development. We assume that CBsv is produced in growing oocytes to keep them in prophase, and during embryogenesis to slow down cell cycle in cells that will be committed to differentiation.
Abbreviations used in this paper: 1-MeAde, 1-methyl-adenine; aa, amino acid; CB, cyclin B; CBsv, CB splice variant; CDK, cyclin-dependent kinase; CRS, cytoplasmic retention signal; GVBD, germinal vesicle breakdown; MPF, M-phase–promoting factor; nt, nucleotide; ORF, open reading frame; RT, reverse transcriptase.
Jean-Claude Lozano and Philippe Schatt contributed equally to this work.
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