Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have created two mutants of mouse transcription factor c-Rel (c-G29E and c-R266H) that are analogous to mutants previously shown to have temperature-sensitive (ts) functions for the homologous Drosophila protein Dorsal and the retroviral oncoprotein v-Rel. In vitro, c-R266H shows both a ts and a concentration-dependent ability to bind DNA, suggesting that the lesion affects the ability of c-Rel to form homodimers. In contrast, the ability of mouse c-G29E to bind DNA in vitro is not ts. c-Rel mutant c-R266H also shows a ts ability to activate transcription from a kappaB-site reporter plasmid, whereas c-G29E activates transcription well above control levels at both 33 and 39 degrees C. Insertion of two amino acids (Pro-Trp) between amino acids 266 and 267 in mouse c-Rel (mutant c-SPW) also creates a c-Rel protein with distinct properties: mutant c-SPW is partially defective in that it cannot form DNA-binding homodimers but can form DNA-binding heterodimers with p50. Interestingly, the mutations in c-Rel that affect homodimer formation (c-R266H and c-SPW) fall within a consensus protein kinase A recognition sequence but are not predicted to lie in the dimer interface. Conditional and partially defective mutants such as those described herein may be useful for identifying physiological responses and genes regulated by specific Rel/NF-kappaB family members.
...
PMID:Mutations within a conserved protein kinase A recognition sequence confer temperature-sensitive and partially defective activities onto mouse c-Rel. 1284 86

Stanniocalcin (STC) is a large polypeptide hormone that is widely distributed in tissues such as kidney, adrenal, and ovary. In most tissues, STC exists as a 50-kDa homodimer (STC50). The ovaries produce a higher molecular weight variant (big STC) in androgen-producing theca cell and interstitial cell compartments. Luteal cells, which do not express the STC gene, nonetheless contain high levels of STC protein, suggesting they are targeted by and sequester big STC through a receptor-mediated process. Recently, an STC.alkaline phosphatase fusion protein was used to characterize mitochondrial targeting and sequestration of STC50 and its receptor in liver and kidney. The main objective of the present study was to characterize big STC and its receptor in mammalian ovary and determine whether the ovarian STC variant was similarly targeted to luteal cell mitochondria. By in situ ligand binding, we identified large numbers of STC receptors on corpus luteal cells. However, a more detailed analysis of sub-cellular fractions revealed that both STC and its receptor were not preferentially targeted to mitochondria but instead to cholesterol/lipid storage droplets, which was more indicative of a role in steroidogenesis. Functional studies revealed that additions of big STC had concentration-dependent inhibitory effects on both basal and stimulated progesterone output by primary cultured luteal cells. Furthermore, STC receptor levels were up-regulated in luteal cells in response to protein kinase A activation. Taken together, these findings indicate that theca cell-derived big STC is targeted to the cholesterol/lipid storage droplets of luteal cells to regulate steroidogenesis. This constitutes the first reported description of polypeptide hormone and receptor targeting to cholesterol/lipid droplets and the first biological role for the big STC variant.
...
PMID:Targeting of big stanniocalcin and its receptor to lipid storage droplets of ovarian steroidogenic cells. 1451 26

The endoplasmic reticulum (ER), which plays important roles in apoptosis, is susceptible to oxidative stress. Because reactive oxygen species (ROS) are robustly produced in the ischemic brain, ER damage by ROS may be implicated in ischemic neuronal cell death. We induced global brain ischemia on wild-type and copper/zinc superoxide dismutase (SOD1) transgenic rats and compared ER stress and neuronal damage. Phosphorylated forms of eukaryotic initiation factor 2 alpha (eIF2 alpha) and RNA-dependent protein kinase-like ER eIF2 alpha kinase (PERK), both of which play active roles in apoptosis, were increased in hippocampal CA1 neurons after ischemia but to a lesser degree in the transgenic animals. This finding, together with the finding that the transgenic animals showed decreased neuronal degeneration, indicates that oxidative ER damage is involved in ischemic neuronal cell death. To elucidate the mechanisms of ER damage by ROS, we analyzed glucose-regulated protein 78 (GRP78) binding with PERK and oxidative ER protein modification. The proteins were oxidatively modified and stagnated in the ER lumen, and GRP78 was detached from PERK by ischemia, all of which were attenuated by SOD1 overexpression. We propose that ROS attack and modify ER proteins and elicit ER stress response, which results in neuronal cell death.
...
PMID:Oxidative damage to the endoplasmic reticulum is implicated in ischemic neuronal cell death. 1452 22

We present structural data on the RI alpha isoform of the cAMP-dependent protein kinase A that reveal, for the first time, a large scale conformational change within the RI alpha homodimer upon catalytic subunit binding. This result infers that the inhibition of catalytic subunit activity is not the result of a simple docking process but rather is a multi-step process involving local conformational changes both in the cAMP-binding domains as well as in the linker region of the regulatory subunit that impact the global structure of the regulatory homodimer. The results were obtained using small-angle neutron scattering with contrast variation and deuterium labeling. From these experiments we derived information on the shapes and dispositions of the catalytic subunits and regulatory homodimer within a holoenzyme reconstituted with a deuterated regulatory subunit. The scattering data also show that, despite extensive sequence homology between the isoforms, the overall structure of the type I alpha holoenzyme is significantly more compact than the type II alpha isoform. We present a model of the type I alpha holoenzyme, built using available high-resolution structures of the component subunits and domains, which best fits the neutron-scattering data. In this model, the type I alpha holoenzyme forms a flattened V shape with the RI alpha dimerization domain at the point of the V and the cAMP-binding domains of the RI alpha subunits with their bound catalytic subunits at the ends.
...
PMID:C subunits binding to the protein kinase A RI alpha dimer induce a large conformational change. 1498 29

In the yeast Saccharomyces cerevisiae, starvation for amino acids induces phosphorylation of the alpha subunit of eukaryotic initiation factor 2alpha by Gcn2 protein kinase, leading to elevated translation of GCN4. Gcn4p is a transcriptional activator of hundreds of genes involved in remedying nutrient deprivation. In addition to a conserved kinase domain, Gcn2p has a regulatory region homologous to histidyl tRNA synthetase enzymes that binds uncharged tRNA that accumulates during amino acid starvation. Flanking the carboxyl terminus of the histidyl-tRNA synthetase-related domain is a region spanning 162 residues that participates in the activation of the protein kinase. Gel filtration and chemical cross-linking analysis of the recombinant carboxyl-terminal Gcn2 protein revealed that this region is a stable homodimer that is highly resistant to high concentrations of salt. Residue alterations in three hydrophobic segments and one segment with a proposed amphipathic alpha-helix in this Gcn2p carboxyl terminus blocked oligomerization, supporting the role of hydrophobic interactions in the dimerization interface of Gcn2p. Introduction of residue substitutions that impaired dimerization into the full-length protein prevented the ability of Gcn2p to phosphorylate its substrate eukaryotic initiation factor-2alpha and induce GCN4 translational expression in yeast cells subjected to a variety of stresses including amino acid limitation or exposure to rapamycin or high levels of NaCl. This latter stress can be overcome by addition of increasing amounts of K+ ions, indicating that the Na+/K+ ion balance is central to this stress induction. We conclude that dimerization involving hydrophobic segments in the carboxyl-terminal region is required for activation of Gcn2p in response to a multitude of stresses.
...
PMID:Dimerization is required for activation of eIF2 kinase Gcn2 in response to diverse environmental stress conditions. 1501 Apr 61

The regulatory (R) subunits of the cAMP-dependent protein kinase (protein kinase A or PKA) are multi-domain proteins responsible for conferring cAMP-dependence and localizing PKA to specific subcellular locations. There are four isoforms of the R subunit in mammals that are similar in molecular mass and domain organization, but clearly serve different biological functions. Although high-resolution structures are available for the cAMP-binding domains and dimerization/docking domains of two isoforms, there are no high-resolution structures of any of the intact R subunit homodimer isoforms. The results of small-angle X-ray scattering studies presented here indicate that the RIalpha, RIIalpha, and RIIbeta homodimers differ markedly in overall shape, despite extensive sequence homology and similar molecular masses. The RIIalpha and RIIbeta homodimers have very extended, rod-like shapes, whereas the RIalpha homodimer likely has a compact Y-shape. Based on a comparison of the R subunit sequences, we predict that the linker regions are the likely cause of these large differences in shape among the isoforms. In addition, we show that cAMP binding does not cause large conformational changes in type Ialpha or IIalpha R subunit homodimers, suggesting that the activation of PKA by cAMP involves only local conformational changes in the R subunits.
...
PMID:Conformational differences among solution structures of the type Ialpha, IIalpha and IIbeta protein kinase A regulatory subunit homodimers: role of the linker regions. 1504 86

Cyclic adenosine 5'-monophosphate (cAMP) is an ancient signaling molecule, and in vertebrates, a primary target for cAMP is cAMP-dependent protein kinase (PKA). (R(p))-adenosine 3',5'-cyclic monophosphothioate ((R(p))-cAMPS) and its analogues are the only known competitive inhibitors and antagonists for cAMP activation of PKA, while (S(p))-adenosine 3',5'-cyclic monophosphothioate ((S(p))-cAMPS) functions as an agonist. The crystal structures of a Delta(1-91) deletion mutant of the RIalpha regulatory subunit of PKA bound to (R(p))-cAMPS and (S(p))-cAMPS were determined at 2.4 and 2.3 A resolution, respectively. While the structures are similar to each other and to the crystal structure of RIalpha bound to cAMP, differences in the dynamical properties of the protein when (R(p))-cAMPS is bound are apparent. The structures highlight the critical importance of the exocyclic oxygen's interaction with the invariant arginine in the phosphate binding cassette (PBC) and the importance of this interaction for the dynamical properties of the interactions that radiate out from the PBC. The conformations of the phosphate binding cassettes containing two invariant arginine residues (Arg209 on domain A, and Arg333 on domain B) are somewhat different due to the sulfur interacting with this arginine. Furthermore, the B-site ligand together with the entire domain B show significant differences in their overall dynamic properties in the crystal structure of Delta(1-91) RIalpha complexed with (R(p))-cAMPS phosphothioate analogue ((R(p))-RIalpha) compared to the cAMP- and (S(p))-cAMPS-bound type I and II regulatory subunits, based on the temperature factors. In all structures, two structural solvent molecules exist within the A-site ligand binding pocket; both mediate water-bridged interactions between the ligand and the protein. No structured waters are in the B-site pocket. Owing to the higher resolution data, the N-terminal segment (109-117) of the RIalpha subunit can also be traced. This strand forms an intermolecular antiparallel beta-sheet with the same strand in an adjacent molecule and implies that the RIalpha subunit can form a weak homodimer even in the absence of its dimerization domain.
...
PMID:Crystal structures of RIalpha subunit of cyclic adenosine 5'-monophosphate (cAMP)-dependent protein kinase complexed with (Rp)-adenosine 3',5'-cyclic monophosphothioate and (Sp)-adenosine 3',5'-cyclic monophosphothioate, the phosphothioate analogues of cAMP. 1515 95

Fru-2,6-P2 (fructose 2,6-bisphosphate) is a signal molecule that controls glycolysis. Since its discovery more than 20 years ago, inroads have been made towards the understanding of the structure-function relationships in PFK-2 (6-phosphofructo-2-kinase)/FBPase-2 (fructose-2,6-bisphosphatase), the homodimeric bifunctional enzyme that catalyses the synthesis and degradation of Fru-2,6-P2. The FBPase-2 domain of the enzyme subunit bears sequence, mechanistic and structural similarity to the histidine phosphatase family of enzymes. The PFK-2 domain was originally thought to resemble bacterial PFK-1 (6-phosphofructo-1-kinase), but this proved not to be correct. Molecular modelling of the PFK-2 domain revealed that, instead, it has the same fold as adenylate kinase. This was confirmed by X-ray crystallography. A PFK-2/FBPase-2 sequence in the genome of one prokaryote, the proteobacterium Desulfovibrio desulfuricans, could be the result of horizontal gene transfer from a eukaryote distantly related to all other organisms, possibly a protist. This, together with the presence of PFK-2/FBPase-2 genes in trypanosomatids (albeit with possibly only one of the domains active), indicates that fusion of genes initially coding for separate PFK-2 and FBPase-2 domains might have occurred early in evolution. In the enzyme homodimer, the PFK-2 domains come together in a head-to-head like fashion, whereas the FBPase-2 domains can function as monomers. There are four PFK-2/FBPase-2 isoenzymes in mammals, each coded by a different gene that expresses several isoforms of each isoenzyme. In these genes, regulatory sequences have been identified which account for their long-term control by hormones and tissue-specific transcription factors. One of these, HNF-6 (hepatocyte nuclear factor-6), was discovered in this way. As to short-term control, the liver isoenzyme is phosphorylated at the N-terminus, adjacent to the PFK-2 domain, by PKA (cAMP-dependent protein kinase), leading to PFK-2 inactivation and FBPase-2 activation. In contrast, the heart isoenzyme is phosphorylated at the C-terminus by several protein kinases in different signalling pathways, resulting in PFK-2 activation.
...
PMID:6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: head-to-head with a bifunctional enzyme that controls glycolysis. 1517 Mar 86

Aerobic cells adjust the expression of antioxidant enzymes to maintain reactive oxygen species within tolerable levels. In addition, phosphatidylinositol 3 kinase (PI3K) and its downstream protein kinase effector Akt adapt cells to survive in the presence of oxidative stress. Here we provide evidence for an association between these two defense systems via transcriptional regulation of Cu/Zn-superoxide dismutase (Cu/Zn-SOD). PC12 pheochromocytoma cells expressing active Akt1 exhibit lower ROS levels in response to hydrogen peroxide, as determined with the superoxide-sensitive probe hydroethidine. Transfection of constitutive or 4-hydroxytamoxifen-inducible versions of Akt1 results in higher messenger RNA and protein levels of Cu/Zn-SOD. Luciferase reporter constructs, carrying different length fragments of the human sod1 gene promoter, have identified a region between -552 and -355 that is targeted by PI3K and Akt and that contains a putative site of regulation by nuclear factor-kappaB (NF-kappaB). Nerve growth factor (NGF) and Akt augment the transactivating activity and produce higher nuclear levels of p65-NF-kappaB. Electrophoretic mobility shift assays indicate that the putative NF-kappaB regulatory sequence binds p65-NF-kappaB more efficiently in nuclear extracts from these cells. A dominant-negative mutant of IkappaBalpha further demonstrates that the PI3K/Akt axis targets the sod1 promoter at the level of the newly characterized NF-kappaB site. These results illustrate a new mechanism by which the PI3K/Akt pathway protects cells against oxidative stress, involving the upregulation of Cu/Zn-SOD gene expression, and the results identify NF-kappaB as a key mediator in the regulation of this gene.
...
PMID:Regulation of Cu/Zn-superoxide dismutase expression via the phosphatidylinositol 3 kinase/Akt pathway and nuclear factor-kappaB. 1531 58

This study was undertaken to evaluate the effect of the G93A mutation in the human Cu/Zn-superoxide dismutase gene (hSOD1) on the phosphatidylinositol-3-kinase (PI3K)/Akt and glycogen synthase kinase-3 (GSK-3) pathway in motoneuron, and to determine the role of epigallocatechin gallate (EGCG) on oxidative stress-injured motoneurons. The viability of G93A mutant cells was less than that of wild-type cells, and the activation of PI3K and the phosphorylation of Akt and GSK-3 in G93A mutant cells decreased compared with wild-type hSOD1 4.1 cells. In the experiment to evaluate the effect of oxidative stress and/or EGCG on these motoneurons, after exposure to 400 microM H2O2, the MTT assay revealed greatly reduced viability of G93A mutant cells compared with wild-type cells, and pre-treatment of these cells with EGCG before H2O2 exposure increased the viability of both cell lines. Western blot analysis showed that the G93A mutation and oxidative stress decreased survival signals including PI3K/Akt but increased death signals including GSK-3; however, pre-treatment with EGCG increased survival signals but decreased death signals. These results suggest that PI3K/Akt and GSK-3 activities are altered in G93A mutant cells and EGCG-induced activation of PI3K/Akt and inhibition of GSK-3 could be a new potential therapeutic strategy for ALS associated with oxidative injury.
...
PMID:Epigallocatechin gallate prevents oxidative-stress-induced death of mutant Cu/Zn-superoxide dismutase (G93A) motoneuron cells by alteration of cell survival and death signals. 1533 84


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---