The TAO of MEKK.
Cloning and characterization of MEKK1 in 1993 revealed that in addition to Raf there were other pathways activated by extracellular stimuli that were responsible for ERK activation. Since then, three additional MEKK family members have been cloned adding even further diversity to the regulation of MAPK pathways. The MEKK family members are regulated by a diverse array of extracellular stimuli ranging from growth factors to DNA damaging stimuli and so are important for the cell to sense exposure to various environmental stimuli. One important aspect of MEKK biology is that they can potentially serve in more than one pathway. Regulation of MEKK family members often involves LMWG proteins, phosphorylation and subcellular localization. With regard to at least MEKK1, serine/threonine kinases such as NIK, GLK and HPK1 appear also to be important for regulation. Of the MEKK family members, the biological role of MEKK1 is best characterized and studies have shown that MEKK1 is important in mediating survival vs. apoptosis, possibly via its ability to regulate transcription factors, the expression of death receptors and their ligands. The biological roles of MEKK2, 3 and 4 are under investigation and undoubtedly homologous deletion of these MEKK family members will be invaluable at determining the biological functions of these MEKKs. At present, the MEKK family members are characterized as localized sensors that control cell responses at the level of gene expression, metabolism and the cytoskeleton
Schlesinger
T K
TK
Program in Molecular Signal Transduction, Division of Basic Sciences, National Jewish Medical and Research Center, 1400 Jackson St. Denver, CO 80206, USA.
Fanger
G R
GR
Yujiri
T
T
Johnson
G L
GL
D000818:Animals; D017209:Apoptosis; D002470:Cell Survival; D006801:Humans; D048370:MAP Kinase Kinase 2; D048371:MAP Kinase Kinase 3; D048670:MAP Kinase Kinase 4; D048728:MAP Kinase Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction
D016328:NF-kappa B; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D048370:MAP Kinase Kinase 2; D048371:MAP Kinase Kinase 3; D048670:MAP Kinase Kinase 4; C482530:MAP2K3 protein, human; C482559:MAP2K4 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases