Abstract
Cdc2, the cyclin-dependent kinase that controls mitosis, is negatively regulated by phosphorylation on its threonine-14 and tyrosine-15 residues. Cdc25, the phosphatase that dephosphorylates both of these residues, undergoes activation and phosphorylation by multiple kinases at mitosis. Plx1, a kinase that associates with and phosphorylates the amino-terminal domain of Cdc25, was purified extensively from Xenopus egg extracts. Cloning of its complementary DNA revealed that Plx1 is related to the Polo family of protein kinases. Recombinant Plx1 phosphorylated Cdc25 and stimulated its activity in a purified system. Cdc25 phosphorylated by Plx1 reacted strongly with MPM-2, a monoclonal antibody to mitotic phosphoproteins. These studies indicate that Plx1 may participate in control of mitotic progression.
Publication types
-
Research Support, Non-U.S. Gov't
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
Amino Acid Sequence
-
Animals
-
Base Sequence
-
CDC2 Protein Kinase / metabolism
-
Cell Cycle Proteins / chemistry
-
Cell Cycle Proteins / metabolism*
-
Cloning, Molecular
-
Cyclins / metabolism
-
Enzyme Activation
-
Molecular Sequence Data
-
Mutation
-
Oocytes / enzymology
-
Peptide Mapping
-
Phosphoprotein Phosphatases / chemistry
-
Phosphoprotein Phosphatases / metabolism*
-
Phosphorylation
-
Phosphoserine / analysis
-
Phosphothreonine / analysis
-
Protein Serine-Threonine Kinases / chemistry
-
Protein Serine-Threonine Kinases / genetics
-
Protein Serine-Threonine Kinases / isolation & purification*
-
Protein Serine-Threonine Kinases / metabolism
-
Recombinant Proteins / metabolism
-
Xenopus
-
Xenopus Proteins*
-
cdc25 Phosphatases
Substances
-
Cell Cycle Proteins
-
Cyclins
-
Recombinant Proteins
-
Xenopus Proteins
-
Phosphothreonine
-
Phosphoserine
-
Plk1 protein, Xenopus
-
Protein Serine-Threonine Kinases
-
CDC2 Protein Kinase
-
Phosphoprotein Phosphatases
-
cdc25 Phosphatases