SGEBP, a giant protein from starfish oocytes able to interact with ERK.

The mitogen-activated protein kinase (MAPK) pathway is a key regulator of animal meiotic divisions. It involves cascades of kinases whose specificity has been shown to depend on binding proteins acting as scaffolds. We searched for proteins interacting with starfish extracellular signal-regulated kinase (ERK) using the yeast two-hybrid system.

Evolution of cyclin B3 shows an abrupt three-fold size increase, due to the extension of a single exon in placental mammals, allowing for new protein-protein interactions.

Cyclin B3 evolution has the unique peculiarity of an abrupt 3-fold increase of the protein size in the mammalian lineage due to the extension of a single exon. We have analyzed the evolution of the gene to define the modalities of this event and the possible consequences on the function of the protein. Database searches can trace the appearance of the gene to the origin of metazoans.

CDK5 is present in sea urchin and starfish eggs and embryos and can interact with p35, cyclin E and cyclin B3.

While most cyclin-dependent kinases (CDKs) are involved in cell cycle control, CDK5 is mostly known for crucial functions in neurogenesis. However, we cloned sea urchin CDK5 from a two-cell stage cDNA library and found that the protein is present in eggs and embryos, up to the pluteus stage, but without associated kinase activity. To investigate the potential for nonneuronal roles, we screened a starfish cDNA library with the yeast two-hybrid system, for possible CDK5 partners.

Cyclin B synthesis and rapamycin-sensitive regulation of protein synthesis during starfish oocyte meiotic divisions.

Translation of cyclin mRNAs represents an important event for proper meiotic maturation and post-fertilization mitoses in many species. Translational control of cyclin B mRNA has been described to be achieved through two separate but related mechanisms: translational repression and polyadenylation. In this paper, we evaluated the contribution of global translational regulation by the cap-dependent translation repressor 4E-BP (eukaryotic initiation factor 4E-binding protein) on the cyclin B protein synthesis during meiotic maturation of the starfish oocytes.

CDC2L5, a Cdk-like kinase with RS domain, interacts with the ASF/SF2-associated protein p32 and affects splicing in vivo.

The human CDC2L5 gene encodes a protein of unknown physiological function. This protein is closely related to the cyclin-dependent kinase (Cdks) family and contains an arginine/serine-rich (RS) domain. The Cdks were first identified as crucial regulators of cell-cycle progression, more recently they were found to be involved in transcription and mRNA processing.