High impact information on xcdc25-3

• Oscillation of MPF is accompanied by periodic association between cdc25 and cdc2-cyclin B [1].
• We find that Xenopus oocytes contain a relative of cdc25, p72 [1].
• Moreover, treatment of interphase Xenopus extracts with okadaic acid, a phosphatase inhibitor that accelerates the entry into mitosis, elicits both the premature hyperphosphorylation of cdc25 and the stimulation of its cdc2-specific tyrosine phosphatase activity [2].
• Near the onset of mitosis, the cdc25 protein undergoes a marked elevation in phosphatase activity that coincides with an extensive phosphorylation of the protein in its N-terminal region [2].
• Regulation of the cdc25 protein during the cell cycle in Xenopus extracts [2].

Biological context of xcdc25-3

• The cdc25 protein is a highly specific tyrosine phosphatase that triggers mitosis by dephosphorylating the cdc2 protein kinase [2].
• Using Xenopus extracts, we have found that the cdc25 protein is active at a low level throughout interphase [2].
• Genetic studies have demonstrated that the cdc25 protein activates the cdc2 protein kinase once DNA replication has been completed [3].
• These biochemical experiments demonstrate that the cdc25 protein actively drives tyrosine dephosphorylation of the cdc2 protein and offer the prospect for characterizing the individual factors that regulate the activation of MPF during the progression from S phase to mitosis [3].
• Progesterone induces a cytoplasmic signaling pathway that leads to activation of cdc25, the phosphatase that removes these phosphorylations, catalyzing entry into M phase [4].

Anatomical context of xcdc25-3

• The cdc25 protein controls tyrosine dephosphorylation of the cdc2 protein in a cell-free system [3].

Associations of xcdc25-3 with chemical compounds

• These experiments demonstrate the existence of a cdc25 regulatory system consisting of both a stimulatory kinase that phosphorylates a putative regulatory domain of the cdc25 protein and an inhibitory serine/threonine phosphatase that counteracts this kinase activity [2].

Enzymatic interactions of xcdc25-3

• (ii) Endogenous cdc25 is phosphorylated on Ser-287 in oocytes and dephosphorylated in response to progesterone just before cdc2 dephosphorylation and M-phase entry [4].

Other interactions of xcdc25-3

• Two major peaks of cdc25 dephosphorylating activities were detected during the sequential chromatography, one that copurified with the major peak of MPM-2 epitope phosphatase activity, and the other with the major peak of PP2A activity [5].
• (i) In vitro, cdc25 Ser-287 serves as a major site of phosphorylation by PKA, resulting in sequestration by 14-3-3 [4].

References