title: Molecular cloning and characterization of a novel protein kinase with a catalytic domain homologous to mitogen-activated protein kinase kinase kinase.
abstract: Mitogen-activated protein kinase (MAPK) signaling cascades include MAPK or extracellular signal-regulated kinase (ERK), MAPK kinase (MKK or MEK), and MAPK kinase kinase (MAPKKK or MEKK). MAPKK kinase/MEKK phosphorylates and activates its downstream protein kinase, MAPK kinase/MEK, which in turn activates MAPK. We report herein the isolation of a cDNA encoding a novel protein kinase designated MAPKKK5 from a human macrophage library. The nucleotide sequence predicts that MAPKKK5 encodes an open reading frame of 1374 amino acids with all 11 kinase subdomains. The putative catalytic domain of MAPKKK5 shows significant sequence homology to the kinase domains of the MAPKKK/MEKK level protein kinases from mouse MEKK2 and -3, Drosophila melanogaster PK92B, Saccharomyces cerevisiae STE11, and Schizosaccharomyces pombe BYR2. Northern blot analysis showed that MAPKKK5 transcript is abundantly expressed in human heart and pancreas. When transiently expressed in COS and 293 cells, MAPKKK5 markedly activated c-Jun N-terminal kinase or stress-activated protein kinase, but not MAPK/ERK. Furthermore, MAPKKK5 that was immunoprecipitated from transfected 293 cells was able to phosphorylate and activate MKK4 in vitro, suggesting that MAPKKK5 may be an upstream activator of MKK4 in the c-Jun N-terminal kinase pathway.
authors.affiliation: Amgen, Inc., Boulder, Colorado 80301, USA.
authors.forename: X S
authors.initials: XS
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Diener
authors.forename: D
authors.initials: D
authors.lastname: Jannuzzi
authors.forename: D
authors.initials: D
authors.lastname: Trollinger
authors.forename: T H
authors.initials: TH
authors.lastname: Tan
authors.forename: H
authors.initials: H
authors.lastname: Lichenstein
authors.forename: M
authors.initials: M
authors.lastname: Zukowski
authors.forename: Z
authors.initials: Z
authors.lastname: Yao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D003001:Cloning, Molecular; D004789:Enzyme Activation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D012333:RNA, Messenger; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; C482858:MAP3K5 protein, human; C482859:Map3k5 protein, mouse