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MEK1 |
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| Sequential activation of protein kinases within the MAPK (mitogen-activated protein kinases) cascades is a common mechanism of signal transduction in many cellular processes. The ERK signaling cascade is a central MAPK pathway that plays a role in the regulation of various cellular processes such as proliferation, differentiation, development, learning, and survival. Mitogen-activated protein kinase kinases (MAPKK) phosphorylate MAPK. MEK (MAP kinase or ERK kinase) is the immediate upstream activator kinase of ERK.
The human MEK1 encodes 393 amino acid residues and shares 99% amino acid sequence identity with the murine MEKl and 80% with human MEK2 (400 amino acids). The MEKs constitute an evolutionarily conserved group of three highly homologous mammalian isoforms. These are the 45 kDa MEK1, its alternatively spliced form, MEK1b (43 kDa) that is thought to be inactive, and the 46 kDa MEK2. These proteins are composed of a catalytic kinase domain, which is surrounded by a regulatory N-terminal domain ( 80 amino acids) and a shorter C-terminal region ( 30 amino acids). MEKs are activated by phosphorylation of two Ser residues in their activation loop (Ser218 and Ser222 in MEK1). The activity of MEKs is regulated by additional phosphorylation/dephosphorylation processes as well. |
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1) Shaul YD and Seger R, 2007, Biochim Biophys Acta. 1773(8):1213-1226.
2) Rubinfeld H and Seger R, 2005, Mol Biotechnol. 31(2):151-174
3) Zheng CF and Guan KL, 1993, J. Biol. Chem. 268:11435-11439.
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