MNK1, a new MAP kinase-activated protein kinase, isolated by a novel expression screening method for identifying protein kinase substrates.
We have developed a novel expression screening method for identifying protein kinase substrates. In this method, a lambda phage cDNA expression library is screened by in situ, solid-phase phosphorylation using purified protein kinase and [gamma-32P]ATP. Screening a HeLa cDNA library with ERK1 MAP kinase yielded cDNAs of previously characterized ERK substrates, c-Myc and p90RSK, demonstrating the utility of this method for identifying physiological protein kinase substrates. A novel clone isolated in this screen, designated MNK1, encodes a protein-serine/threonine kinase, which is most similar to MAP kinase-activated protein kinase 2 (MAPKAP-K2), 3pK/MAPKAP-K3 and p90RSK. Bacterially expressed MNK1 was phosphorylated and activated in vitro by ERK1 and p38 MAP kinases but not by JNK/SAPK. Further, MNK1 was activated upon stimulation of HeLa cells with 12-O-tetradecanoylphorbol-13-acetate, fetal calf serum, anisomycin, UV irradiation, tumor necrosis factor-alpha, interleukin-1beta, or osmotic shock, and the activation by these stimuli was differentially inhibited by the MEK inhibitor PD098059 or the p38 MAP kinase inhibitor SB202190. Together, these results indicate that MNK1 is a novel class of protein kinase that is activated through both the ERK and p38 MAP kinase signaling pathways.
Fukunaga
R
R
Molecular Biology and Virology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Hunter
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods*; D018076:DNA, Complementary / Q000235:genetics; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology; D018411:Spodoptera; D013379:Substrate Specificity; D048051:p38 Mitogen-Activated Protein Kinases
D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D011725:Pyridines; D011993:Recombinant Fusion Proteins; C491395:MKNK1 protein, human; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one