6una
Crystal structure of inactive p38gamma
Structural highlights
DiseaseMK12_HUMAN Note=MAPK is overexpressed in highly metastatic breast cancer cell lines and its expression is preferentially associated with basal-like and metastatic phenotypes of breast tumor samples. FunctionMK12_HUMAN Serine/threonine kinase which acts as an essential component of the MAP kinase signal transduction pathway. MAPK12 is one of the four p38 MAPKs which play an important role in the cascades of cellular responses evoked by extracellular stimuli such as proinflammatory cytokines or physical stress leading to direct activation of transcription factors such as ELK1 and ATF2. Accordingly, p38 MAPKs phosphorylate a broad range of proteins and it has been estimated that they may have approximately 200 to 300 substrates each. Some of the targets are downstream kinases such as MAPKAPK2, which are activated through phosphorylation and further phosphorylate additional targets. Plays a role in myoblast differentiation and also in the down-regulation of cyclin D1 in response to hypoxia in adrenal cells suggesting MAPK12 may inhibit cell proliferation while promoting differentiation. Phosphorylates DLG1. Following osmotic shock, MAPK12 in the cell nucleus increases its association with nuclear DLG1, thereby causing dissociation of DLG1-SFPQ complexes. This function is independent of its catalytic activity and could affect mRNA processing and/or gene transcription to aid cell adaptation to osmolarity changes in the environment. Regulates UV-induced checkpoint signaling and repair of UV-induced DNA damage and G2 arrest after gamma-radiation exposure. MAPK12 is involved in the regulation of SLC2A1 expression and basal glucose uptake in L6 myotubes; and negatively regulates SLC2A4 expression and contraction-mediated glucose uptake in adult skeletal muscle. C-Jun (JUN) phosphorylation is stimulated by MAPK14 and inhibited by MAPK12, leading to a distinct AP-1 regulation. MAPK12 is required for the normal kinetochore localization of PLK1, prevents chromosomal instability and supports mitotic cell viability. MAPK12-signaling is also positively regulating the expansion of transient amplifying myogenic precursor cells during muscle growth and regeneration.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedThe inactive state of mitogen-activated protein kinases (MAPKs) adopts an open conformation while the active state exists in a compact form stabilized by phosphorylation. In the active state, eukaryotic kinases undergo breathing motions related to substrate binding and product release that have not previously been detected in the inactive state. However, docking interactions of partner proteins with inactive MAPK kinases exhibit allostery in binding of activating kinases. Interactions at a site distant from the activation loop are coupled to the configuration of the activation loop, suggesting that the inactive state may also undergo concerted dynamics. X-ray crystallographic studies of nonphosphorylated, inactive p38gamma reveal differences in domain orientations and active site structure in the two molecules in the asymmetric unit. One molecule resembles an inactive kinase with an open active site. The second molecule has a rotation of the N-lobe that leads to partial compaction of the active site, resulting in a conformation that is intermediate between the inactive open state and the fully closed state of the activated kinase. Although the compact state of apo p38gamma displays several of the features of the activated enzyme, it remains catalytically inert. In solution, the kinase fluctuates on a millisecond time scale between the open ground state and a weakly populated excited state that is similar in structure to the compact state observed in the crystal. The nuclear magnetic resonance and crystal structure data imply that interconversion between the open and compact states involves a molecular switch associated with the DFG loop. A Dynamic Switch in Inactive p38gamma Leads to an Excited State on the Pathway to an Active Kinase.,Aoto PC, Stanfield RL, Wilson IA, Dyson HJ, Wright PE Biochemistry. 2019 Dec 13. doi: 10.1021/acs.biochem.9b00932. PMID:31794659[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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