Protein kinase expression

El-Husseini AE, Bladen C, Vincent SR (1995) Molecular characterization of a type II cyclic GMP-dependent protein kinase expressed in the rat brain. J Neurochem 64 2814-7... 

Our laboratory has provided significant contributions in the area of myristoyla-tion. We discovered and purified the myristoyl-CoA binding protein (MCBP) from bovine cardiac muscle (Raju and Sharma 1997). In cardiac tissues there is a high level of cAMP-dependent protein kinase expression whose catalytic subunit is myristoylated (Carr et al. 1982). The catalytic subunit of cAMP-dependent protein kinase and the beta subunit of calcineurin are myristoylated proteins localized in the cytoplasm (Selvakumar et al. 2006, 2002 Rajala et al. 2000 Johnson et al. 1994 Carr et al. 1982 Aitken et al. 1982). Recently it has been shown that dephosphorylation of the catalytic subunit of myristoylated and nonmyristoylated cAMP-dependent protein kinase at Thr-197 by cellular protein phosphatase and protein... 

We routinely observe that some human protein kinases expressed in insect cells are already phosphorylatedprior to assay. However, many other kinases become newly phosphorylated during this assay. There are two obvious explanations for this first, the autophosphorylation of these latter kinases might simply require the higher ATP concentration used in the assay (compared to in vivo concentrations), or second, that the autophosphorylation event requires dimerization of the kinases in question and that such dimerization is promoted by the surface attachment in the arrays. 

Brophy CM, Woodrum DA, PoUock J, et al. cGMP-dependent protein kinase expression restores contractile function in cultured vascular smooth muscle cells. J Vase Res 2002 39 95-103. 

AMPK can also be activated by a Ca2+-mediated pathway involving phosphorylation at Thr-172 by the Ca2+/calmodulin-dependent protein kinase, CaMKK 3. CaMKKa and CaMKK 3 were discovered as the upstream kinase for the calmodulin-dependent protein kinases-1 and -IV they both activate AMPK in a Ca2+/ calmodulin-dependent manner in cell-free assays, although CaMKK 3 appears to much more active against AMPK in intact cells. Expression of CaMKKa and CaMKK(3 primarily occurs in neural tissues, but CaMKKp is also expressed in some other cell types. Thus, the Ca2+-mediated pathway for AMPK activation has now been shown to occur in response to depolarization in rat neuronal tissue, in response to thrombin (acting via a Gq-coupled receptor) in endothelial cells, and in response to activation of the T cell receptor in T cells. 

Apelin receptors activate several signalling pathways including coupling through inhibitory G-proteins (G ) and Ras-independent activation of extracellular-regulated kinases (ERKs) via protein kinase C (PKC). The apelin receptor is one of number of G-protein-coupled receptors that can act as an alternative coreceptor for entry into cells of HIV and simian immunodeficiency vims (SIV) strains in human U87 cells expressing CD4 in vitro. Apelin peptides blocks entry of HIV but display different potencies, with apelin-36 being more effective than shorter sequences [3]. 

Mitogen activated protein kinase (MARK) cascades are three kinase modules activated by phosphorylation. The three kinase modules are composed of a MAPK, a MAPKK, and a MAPKKK. There are multiple members of each component of the MAPK cascade that are conserved from yeast to human. Activation of selective MAPK modules by specific stimuli regulates cell functions such as gene expression, adhesion, migration, differ entiation, and apoptosis. 

Activation of Mi, M3, and M5 mAChRs does not only lead to the generation of IP3 followed by the mobilization of intracellular Ca2+, but also results in the stimulation of phospholipase A2, phospholipase D, and various tyrosine kinases. Similarly, M2 and M4 receptor activation does not only mediate the inhibition of adenylyl cyclase, but also induces other biochemical responses including augmentation of phospholipase A2 activity. Moreover, the stimulation of different mAChR subtypes is also linked to the activation of different classes of mitogen-activated protein kinases (MAP kinases), resulting in specific effects on gene expression and cell growth or differentiation. 

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