Mitogen-activated protein kinase (MAPK)

Mitogen-activated protein kinase (MAPK) is a class of conserved serine/threonine protein kinases ubiquitous in eukaryotes. The MAPK cascade pathway (MAPKKK-MAPKK-MAPK) is involved in plant growth and development and a variety of biotic and abiotic stress signal transduction through sequential phosphorylation to transmit environmental signals. The MAPKs activation pathway plays a crucial role in the signal transduction process of eukaryotic cells. In 1982, Cooper discovered a protein in the cell (relative molecular mass 42×103) in platelet-derived growth factor and epithelial growth factor research. Phosphorylation of tyrosine residues was followed by (2) 1988, and this protein was also found in phorbol-stimulated cells using two-dimensional electrophoresis. At the same time, Ray also isolated a protein kinase with a molecular mass of 42×103 and phosphorylated threonine and tyrosine residues in insulin-stimulated 3T3L1 cells and named them. For MAPKs. Rossomando (1989) confirmed that the protein phosphorylated by insulin-stimulated threonine/tyrosine residues is phosphorylated with other growth factors and tyrosine residues caused by phorbol lipids. The same substance; the phosphorylation of threonine/tyrosine residues is a necessary condition for the activation of this protein. Boulton (1990) first cloned cDNA encoding MAPKs, and Crews (1993) identified the upstream kinases (MKKKs and MKKs) of MAPKs in mammalian cells using biochemical and molecular cloning techniques and defined a conserved three-kinase. Activation mode. [Composition of MAPKs activation pathway] MAPKs pathway can be activated by various stimuli such as growth factors, cytokines, radiation, neurotransmitters, hormones and cellular stress. The MAPKs activation pathway includes three sequentially activated protein kinases: MKKKs→MKKs→MAPKs. At least 14 MKKKs, 7 MKKs and 12 MAPKs were found in mammalian cells. (1) MKKKs: MKKKs are a serine/threonine protein kinase, and specific MKKKs can be activated by phosphorylation of their kinases (MKKKKs) or by interaction with small G proteins of the Ras or Rho family. Activation; (2) MKKs: Gartner et al. confirmed that MKKs recognize the threonine X tyrosine domain in the activation loop of MAPKs and activate phosphorylation of threonine and tyrosine residues, so MKKs are A dual-specific protein kinase; (3) MAPKs: MAPKs are a class of protein kinases that are widely present in the cytoplasm and have phosphorylation of serine/threonine in the substrate protein molecule. The kinase properties of MAPKs are mediated by proline, which means that only the substrate protein containing proline in the P1 region can be phosphorylated. The substrates of MAPKs are mainly transcription factors, in addition to some protein kinases, phospholipases and cytoskeleton-related proteins. Double phosphorylation of serine and tyrosine residues is essential for MAPKs activation, and different MKKs are able to recognize the spatial structure of the threonine-X-tyrosine domain in specific MAPKs, not just around this activation. A linear sequence of domains.