Subdomain VIII is a specificity-determining region in MEKK1.
MAPK/ERK kinase kinase 1 (MEKK1) is a mitogenactivated protein kinase kinase kinase (MAP3K) of the stress-induced JNK pathway. Once activated, MEKK1 phosphorylates the MAP2K MKK4, which in turn phosphorylates JNK. MEKK1 also has the capacity to activate IKK, the central protein kinase of the NF-kappa B pathway. The molecular determinants responsible for the ability of MEKK1 to recognize specific substrates are poorly understood. We report here that select point mutations in subdomain VIII of the protein kinase domain of MEKK1 (MEKK1 Delta) differentially affect its ability to activate MKK4 and IKK, and consequently AP1 and NF-kappa B reporter genes. Moreover, binding of MKK4 to MEKK1 Delta protects the latter from cleavage at an engineered protease target site in subdomain VIII. Collectively these results provide evidence that subdomain VIII of MEKK1 is involved not only in binding to, but also in discrimination of, protein substrates.
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002384:Catalysis; D004789:Enzyme Activation; D045683:Furin / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D007532:Isoleucine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D048728:MAP Kinase Kinase Kinase 1; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D017354:Point Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014162:Transfection
D007532:Isoleucine; D017346:Protein Serine-Threonine Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; C482578:Map3k1 protein, mouse; D045683:Furin; D007930:Leucine