title: Molecular cloning of mitogen-activated protein/ERK kinase kinases (MEKK) 2 and 3. Regulation of sequential phosphorylation pathways involving mitogen-activated protein kinase and c-Jun kinase.
abstract: Mitogen-activated protein/ERK kinase kinases (MEKKs) phosphorylate and activate protein kinases which in turn phosphorylate and activate the p42/44 mitogen-activated protein kinase (MAPK), c-Jun/stress-activated protein kinases (JNKs), and p38/Hog1 kinase. We have isolated the cDNAs for two novel mammalian MEKKs (MEKK 2 and 3). MEKK 2 and 3 encode proteins of 69.7 and 71 kDa, respectively. The kinase domains encoded in the COOH-terminal moiety are 94% conserved; the NH2-terminal moieties are approximately 65% homologous, suggesting this region may encode sequences conferring differential regulation of the two kinases. Expression of MEKK 2 or 3 in HEK293 cells results in activation of p42/44MAPK and JNK but not of p38/Hog1 kinase. Immunoprecipitated MEKK 2 phosphorylated the MAP kinase kinases, MEK 1, and JNK kinase. Titration of MEKK 2 and 3 expression in transfection assays indicated that MEKK 2 preferentially activated JNK while MEKK 3 preferentially activated p42/44MAPK. These findings define a family of MEKK proteins capable of regulating sequential protein kinase pathways involving MAPK members.
authors.affiliation: Division of Basic Sciences, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Blank
authors.forename: P
authors.initials: P
authors.lastname: Gerwins
authors.forename: E M
authors.initials: EM
authors.lastname: Elliott
authors.forename: S
authors.initials: S
authors.lastname: Sather
authors.forename: G L
authors.initials: GL
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D007700:Kinetics; D048370:MAP Kinase Kinase 2; D048371:MAP Kinase Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014162:Transfection
chemical_list: D000906:Antibodies; D017931:DNA Primers; D018076:DNA, Complementary; D010446:Peptide Fragments; D011994:Recombinant Proteins; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048370:MAP Kinase Kinase 2; D048371:MAP Kinase Kinase 3; C482530:MAP2K3 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases