title: CDC25B phosphorylation by p38 and MK-2.
abstract: CDC25B is one of the three human phosphatases that are involved in the control of the activation of cyclin-dependent kinases. CDC25B participates in regulating entry into mitosis and appears to play a key role in the checkpoint response to DNA injury. CDC25B has been reported to be regulated by a number of kinases and controversial evidence suggests that it is phosphorylated by p38SAPK and/or MAPKAP kinase-2. In this report, we clarify this issue using an approach combining mass spectrometry and the use of specific antibodies against phosphorylated CDC25B residues. We report that MAPKAP kinase-2 phosphorylates CDC25B on multiple sites including S169, S323, S353 and S375, while p38SAPK phosphorylates CDC25B on S249. We show that the S323-phosphorylated form of CDC25B is detected at the centrosome during a normal cell cycle. Since most of these sites are also phosphorylated by several other kinases, our observations highlight the difficulty in characterizing and understanding in vivo phosphorylation patterns.
authors.affiliation: LBCMCP-CNRS UMR5088-IFR109, Institut d'Exploration Fonctionnelle des Génomes, Université Paul Sabatier, Toulouse, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lemaire
authors.forename: Carine
authors.initials: C
authors.lastname: Froment
authors.forename: Rose
authors.initials: R
authors.lastname: Boutros
authors.forename: Odile
authors.initials: O
authors.lastname: Mondesert
authors.forename: Angel R
authors.initials: AR
authors.lastname: Nebreda
authors.forename: Bernard
authors.initials: B
authors.lastname: Monsarrat
authors.forename: Bernard
authors.initials: B
authors.lastname: Ducommun
mesh_terms: D000595:Amino Acid Sequence; D045163:Antibodies, Phospho-Specific / Q000276:immunology; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D020687:cdc25 Phosphatases / Q000737:chemistry / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D045163:Antibodies, Phospho-Specific; D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010748:Phosphopeptides; D010768:Phosphoserine; D017346:Protein Serine-Threonine Kinases; D020687:cdc25 Phosphatases; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C517008:CDC25B protein, human