Synergistic activation by Ras and 14-3-3 protein of a mitogen-activated protein kinase kinase kinase named Ras-dependent extracellular signal-regulated kinase kinase stimulator.
We have identified, in Xenopus oocyte cytosol, a protein kinase named REKS (Ras-dependent extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase kinase (MEK) stimulator), which phosphorylates and activates recombinant ERK2 through recombinant MEK in a recombinant GTP gamma S (guanosine 5'-(3-O-thio)triphosphate)-Ras-dependent manner. We show here that this REKS activity is synergistically enhanced by a combination of mammalian recombinant GTP gamma S-KiRas and 14-3-3 protein purified from rat brain. 14-3-3 protein is known to activate tyrosine and tryptophan hydroxylases, to modulate the protein kinase C activity, to stimulate secretion, and to show phospholipase A2 activity per se. 14-3-3 protein did not affect the MEK activity. 14-3-3 protein neither interacted with Ki-Ras nor affected the neurofibromin activity to stimulate the GTPase activity of Ki-Ras under the conditions where the recombinant N-terminal fragment of c-Raf-1 inhibited it. These results suggest that 14-3-3 protein has an additional function in the regulation of the Ras-MEK-ERK cascade pathway through the activation of REKS.
Shimizu
K
K
Department of Molecular Biology and Biochemistry, Osaka University Medical School, Japan.
Kuroda
S
S
Yamamori
B
B
Matsuda
S
S
Kaibuchi
K
K
Yamauchi
T
T
Isobe
T
T
Irie
K
K
Matsumoto
K
K
Takai
Y
Y
D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases; D005260:Female; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D015689:Oncogene Protein p21(ras) / Q000378:metabolism*; D009865:Oocytes; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D014446:Tyrosine 3-Monooxygenase; D029867:Xenopus Proteins; D014982:Xenopus laevis
D048948:14-3-3 Proteins; D009419:Nerve Tissue Proteins; D029867:Xenopus Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D014446:Tyrosine 3-Monooxygenase; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020930:MAP Kinase Kinase Kinases; C499530:REKS protein, Xenopus; C089319:Ras-dependent mitogen-activated protein kinase kinase kinase; D020929:Mitogen-Activated Protein Kinase Kinases; D015689:Oncogene Protein p21(ras)