title: Isolation of TAO1, a protein kinase that activates MEKs in stress-activated protein kinase cascades.
abstract: Several components of the budding yeast pheromone-response pathway are conserved in mammalian mitogen-activated protein (MAP) kinase pathways. Thus, we used degenerate oligonucleotides derived from the sequence of the Saccharomyces cerevisiae protein kinase Ste20p to amplify related sequences from the rat. One of these sequences was used to clone a rat Ste20p homolog, which we called TAO1 for its one thousand and one amino acids. Northern analysis shows TAO1 is highly expressed in brain, as is a homolog TAO2. Recombinant TAO1 was expressed and purified from Sf9 cells. In vitro, it activated MAP/extracellular signal-regulated protein kinase (ERK) kinases (MEKs) 3, 4, and 6 of the stress-responsive MAP kinase pathways, but not MEK1 or 2 of the classical MAP kinase pathway. TAO1 activated MEK3 but not MEK4 or MEK6 in transfected cells. MEK3 coimmunoprecipitated with TAO1 when they were expressed in 293 cells. In addition, immunoreactive MEK3 endogenous to Sf9 cells copurified with TAO1 produced from a recombinant baculovirus. The activation of and binding to MEK3 by TAO1 implicates TAO1 in the regulation of the p38-containing stress-responsive MAP kinase pathway.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9041, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hutchison
authors.forename: K S
authors.initials: KS
authors.lastname: Berman
authors.forename: M H
authors.initials: MH
authors.lastname: Cobb
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004789:Enzyme Activation; D006801:Humans; D048371:MAP Kinase Kinase 3; D048670:MAP Kinase Kinase 4; D048669:MAP Kinase Kinase 6; D020930:MAP Kinase Kinase Kinases; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D011494:Protein Kinases / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera
chemical_list: D018076:DNA, Complementary; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C115483:TAO1 protein kinase; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020930:MAP Kinase Kinase Kinases; D048371:MAP Kinase Kinase 3; D048670:MAP Kinase Kinase 4; D048669:MAP Kinase Kinase 6; C482530:MAP2K3 protein, human; C482559:MAP2K4 protein, human; C482566:MAP2K6 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases