title: Biochemical characterization of a family of serine/threonine protein kinases regulated by tyrosine and serine/threonine phosphorylations.
abstract: Mitogen-activated protein kinase (p42mapk) becomes transiently activated after treatment of serum-starved murine Swiss 3T3 cells or EL4 thymocytes with a diversity of mitogens. Similarly, a meiosis-activated protein kinase (p44mpk) becomes stimulated during maturation of sea star oocytes induced by 1-methyladenine. Both p42mapk and p44mpk have been identified as protein-serine/threonine kinases that are activated as a consequence of their phosphorylation. Because homologous protein kinases may play essential roles in both mitogenesis and oogenesis, we have compared in detail the biochemical properties of these two kinases. We find that these kinases are highly related based on their in vitro substrate specificities, sensitivity to inhibitors, and immunological cross-reactivity. However, they differ in apparent molecular weight and can be separated chromatographically, indicating that the two enzymes are distinct. Furthermore, in the course of this investigation, we have identified a 44-kDa protein kinase in mitogen-stimulated Swiss mouse 3T3 cells and EL4 thymocytes that co-purifies with p44mpk and thus appears to be a closer homolog of the sea star enzyme. Analysis of these protein kinases clarifies the relationships between a set of tyrosine-phosphorylated 41-45-kDa proteins present in mitogen-stimulated cells (Martinez, R., Nakamura., K. D., and Weber, M. J. (1982) Mol. Cell. Biol. 2, 653-655; Cooper, J. A., and Hunter, T. (1984) Mol. Cell. Biol. 4, 30-37), two myelin basic protein kinases identified in epidermal growth factor-treated Swiss mouse 3T3 cells (Ahn, N. G., Weiel, J. E., Chan, C. P., and Krebs, E. G. (1990) J. Biol. Chem. 265, 11487-11494), and p42mapk. Our work points to the existence of a group of related serine/threonine protein kinases, regulated by tyrosine phosphorylation and functioning at different stages of the cell cycle.
authors.affiliation: Department of Microbiology, University of Virginia Health Sciences Center, Charlottesville 22908.
authors.forename: A J
authors.initials: AJ
authors.lastname: Rossomando
authors.forename: J S
authors.initials: JS
authors.lastname: Sanghera
authors.forename: L A
authors.initials: LA
authors.lastname: Marsden
authors.forename: M J
authors.initials: MJ
authors.lastname: Weber
authors.forename: S L
authors.initials: SL
authors.lastname: Pelech
authors.forename: T W
authors.initials: TW
authors.lastname: Sturgill
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002853:Chromatography, Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D015971:Gene Expression Regulation, Enzymologic; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D005810:Multigene Family; D010449:Peptide Mapping; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases; D012615:Sea Anemones; D013379:Substrate Specificity; D014443:Tyrosine / Q000378:metabolism
chemical_list: D047428:Protein Kinase Inhibitors; D014443:Tyrosine; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases