Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.26 (GSK)
 6,788 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tau protein from Alzheimer disease (AD) brain is phosphorylated at eleven Ser/Thr-Pro and nine Ser/Thr-X sites. The former sites are phosphorylated by proline-dependent protein kinases (PDPKs), the latter by non-PDPKs. The identities of both the PDPKs and non-PDPKs involved in AD tau hyperphosphorylation are still to be established. In this study we have analyzed the interactions between a PDPK (GSK-3) and several non-PDPKs (A-kinase, C-kinase, CK-1, CaM kinase II) in the phosphorylation of one isoform (tau 39) of human tau. We found that the rate of phosphorylation of tau 39 by GSK-3 was increased several-fold if tau were first prephosphorylated by the non-PDPKs. Further, several Alzheimer-like epitopes in tau can be induced only slowly after phosphorylation of tau by GSK-3 alone. After a prephosphorylation of tau by the non-PDPKs, however, the rate of induction of these epitopes by GSK-3 is increased several-fold. These results suggest that one role of non-PDPK-catalyzed phosphorylation is the modulation of PDPK-catalyzed phosphorylation of tau in AD brain.
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PMID:Rapid Alzheimer-like phosphorylation of tau by the synergistic actions of non-proline-dependent protein kinases and GSK-3. 753 Nov 59

During purification of tau protein kinase I and II from the bovine brain extract, a new tau protein kinase was detected and purified with phosphocellulose, gel filtration, S-Sepharose and AF-Heparin column chromatography. The molecular mass of the enzyme was determined to be 32 kDa by gel filtration and activity staining on SDS-PAGE. The enzyme is a Ser/Thr protein kinase phosphorylating tau, beta-tubulin, MAP2 and alpha-casein. Employing many synthetic peptides, the recognition site of this enzyme appears to be -SR-. The enzyme requires no second messenger and is inhibited with high concentration of heparin, but not by inhibitors of CKI. These results indicate that this enzyme, tau-tubulin kinase is novel and distinct from TPKI, II and CKI, II.
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PMID:A novel tau-tubulin kinase from bovine brain. 755 43

Tau protein, the major component of the aberrant structures termed paired helical filaments (PHFs) present in the brain of Alzheimer's disease patients, is pathologically phosphorylated in sites in and around the tubulin-binding sites. A single protein kinase, glycogen synthase kinase 3 (GSK 3), is able to phosphorylate tau at the flanking regions and, additionally, at the tubulin-binding motifs if heparin or tubulin is present. Serines-262 and -324 have been found to be modified at the tubulin-binding region of tau protein by GSK 3 in the presence of heparin or tubulin.
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PMID:Glycogen synthase kinase 3 phosphorylates recombinant human tau protein at serine-262 in the presence of heparin (or tubulin). 755 45

Petunia hybrida ovule-specific cDNA libraries were screened for genes encoding homologues of protein kinases known to be involved in developmental processes. Two cDNAs, PSK4 and PSK6 (Petunia hybrida shaggy related protein kinase), homologous to GSK-3 from rat, MDS1 from yeast and to the segment polarity gene shaggy/zeste-white 3 (sgg/zw3) from Drosophila were characterized in detail. Southern blot analysis showed that the PSK4 and PSK6 genes belong to a small multigene family in P. hybrida. The PSK4 and PSK6 proteins, which are 70% identical to sgg/zw3 and its functional homologue GSK-3 over the protein kinase catalytic domain and 55% identical to MDS1, represent two different subgroups of protein kinases. RNA gel blot and RT-PCR analyses revealed that the PSK4 gene is expressed during the vegetative phase and the female reproductive phase of development and the PSK6 gene predominantly during the male and female reproductive phases. In situ hybridization on developing flower buds confirmed that PSK4 is expressed throughout the different developmental stages from ovule primordium formation until embryo sac maturation, while PSK6 showed expression during anther cell differentiation and at pollen maturity, and an expression pattern similar to PSK4 in the female reproductive organs. The results also revealed transcripts of a PSK gene in embryos at the globular stage.
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PMID:Petunia hybrida homologues of shaggy/zeste-white 3 expressed in female and male reproductive organs. 759 50

The role of the C-terminal domain of CTP: phosphocholine cytidylyltransferase (CT) was explored by the creation of a series of deletion mutations in rat liver cDNA, which were expressed in COS cells as a major protein component. Deletion of up to 55 amino acids from the C-terminus had no effect on the activity of the enzyme, its stimulation by lipid vesicles or on its intracellular distribution between soluble and membrane-bound forms. However, deletion of the C-terminal 139 amino acids resulted in a 90% decrease in activity, loss of response to lipid vesicles and a significant decrease in the fraction of membrane-bound enzyme. Identification of the domain that is phosphorylated in vivo was determined by analysis of 32P-labelled CT mutants and by chymotrypsin proteolysis of purified CT that was 32P-labelled in vivo. Phosphorylation was restricted to the C-terminal 52 amino acids (domain P) and occurred on multiple sites. CT phosphorylation in vitro was catalysed by casein kinase II, cell division control 2 kinase (cdc2 kinase), protein kinases C alpha and beta II, and glycogen synthase kinase-3 (GSK-3), but not by mitogen-activated kinase (MAP kinase). Casein kinase II phosphorylation was directed exclusively to Ser-362. The sites phosphorylated by cdc2 kinase and GSK-3 were restricted to several serines within three proline-rich motifs of domain P. Sites phosphorylated in vitro by protein kinase C, on the other hand, were distributed over the N-terminal catalytic as well as the C-terminal regulatory domain. The stoichiometry of phosphorylation catalysed by any of these kinases was less than 0.2 mol P/mol CT, and no effects on enzyme activity were detected. This study supports a tripartite structure for CT with an N-terminal catalytic domain and a C-terminal regulatory domain comprised of a membrane-binding domain (domain M) and a phosphorylation domain (domain P). It also identifies three kinases as potential regulators in vivo of CT, casein kinase II, cyclin-dependent kinase and GSK-3.
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PMID:Functions of the C-terminal domain of CTP: phosphocholine cytidylyltransferase. Effects of C-terminal deletions on enzyme activity, intracellular localization and phosphorylation potential. 765 14

Recombinant p90rsk expressed from baculovirus was found to be phosphorylated and activated by glycogen synthase kinase-3 (GSK-3) in vitro. Phosphorylation of p90rsk by both GSK-3 alpha and GSK-3 beta isoforms was predominantly on threonine residues. Activated p90rsk, resulting from co-expression in insect cells with the oncogenic protein tyrosine kinase p60v-src, was able to phosphorylate GSK-3 but was a poor GSK-3 substrate. These results suggest a potentially novel regulatory connection in the signal transduction cascades in which p90rsk participates.
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PMID:Phosphorylation and activation of p90rsk by glycogen synthase kinase-3. 769 38

The naphthodianthrone hypericin causes a photosensitized inhibition of protein kinases involved in growth factor signalling pathways. Nanomolar concentrations of hypericin inhibit the protein tyrosine kinase activities (PTK) of the epidermal growth factor receptor and the insulin receptor, while being ineffective towards the cytosolic protein tyrosine kinases Lyn, Fgr, TPK-IIB and CSK. Photosensitized inhibition by hypericin is not restricted to receptor-PTKs since the Ser/Thr protein kinases (protein kinase CK-2, protein kinase C and mitogen-activated kinase) are also extremely sensitive to inhibition (IC50 value for protein kinase CK-2 = 6 nM). A comparison of the hypericin-mediated inhibition of the epidermal growth factor-receptor PTK and protein kinase CK-2 revealed that the inhibition is irreversible, strictly dependent upon irradiation of the enzyme-inhibitor complex with fluorescent light and likely mediated by the formation of radical intermediates (type I mechanism). Although the exact molecular basis for the selectivity of enzyme inhibition by hypericin remains unknown, our results suggest that distantly related protein kinases could still share common reactive domains for the interaction with hypericin.
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PMID:Photosensitized inhibition of growth factor-regulated protein kinases by hypericin. 778 2

The cAMP-dependent protein kinase (PKA) phosphorylates CREB327/341 at a single serine residue, Ser119/133, respectively. Phosphorylation at this site creates the sequence motif SXXXS(P), a consensus site of the glycogen synthase kinase-3 (GSK-3) enzyme (Fiol, C.J., Mahrenholz, A.M., Wang, Y., Roeske, R.W., and Roach, P.J. (1987) J. Biol. Chem. 262, 14042-14048). We examined the phosphorylation of CREB at the SXXXS(P) consensus site and its role in CREB transactivation to cAMP induction. Neither isoform of the GSK-3 enzyme (GSK-3 alpha or beta) utilizes CREB as its substrate unless CREB is already phosphorylated at Ser119/133. A 13-amino acid peptide containing the sequence surrounding Ser119/133 was phosphorylated by GSK-3, at Ser115/129, only after the primary phosphorylation of the peptide by PKA (at Ser119/133), suggesting that Ser115/129 is a GSK-3 phosphoacceptor site. Mutant CREB327/341 proteins containing Ser-->Ala substitutions confirmed Ser115/129 as the only GSK-3 phosphorylation site. Transfection assays of wild type and mutant Gal4-CREB fusion proteins in PC12 cells demonstrated that Ser-->Ala substitution of residue 129 of CREB341 impairs the transcriptional response to cAMP induction. Analogous mutation in CREB327 results in 70% decrease in its transactivation response to cAMP. In undifferentiated F9 cells, which are refractory to cAMP induction, transfected GSK-3 beta kinase induces a 60-fold increase in cyclic AMP response element-dependent transcription, mediated via the endogenous CREB protein. We propose that the hierarchical phosphorylation at the PKA and GSK-3 sites of CREB are essential for cAMP control of CREB.
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PMID:A secondary phosphorylation of CREB341 at Ser129 is required for the cAMP-mediated control of gene expression. A role for glycogen synthase kinase-3 in the control of gene expression. 779 17

The phosphorylation of bovine tau, either by GSK-3 alone or by a combination of GSK-3 and several non-proline-dependent protein kinases (non-PDPKs), was studied. GSK-3 alone catalyzed the incorporation of approximately 3 mol 32P/mol tau at a relatively slow rate. Prephosphorylation of tau by A-kinase, C-kinase, or CK-2 (but not by CK-1, CaM kinase II or Gr kinase) increased both the rate and extent of a subsequent phosphorylation catalyzed by GSK-3 by several-fold. These results suggest that the phosphorylation of tau by PDPKs such as GSK-3 (and possibly MAP kinase, cdk5) may be positively modulated at the substrate level by non-PDPK-catalyzed phosphorylations.
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PMID:Modulation of GSK-3-catalyzed phosphorylation of microtubule-associated protein tau by non-proline-dependent protein kinases. 782 26

We have shown that mitochondrial (mt) transcription in yeast (S. cerevisiae) is governed in part by cAMP via a mt cAMP-dependent protein kinase (cAPK), and that the BCY1 gene product acts as regulatory subunit for that organellar enzyme, as it does for cytoplasmic cAPK. Here we assess mt cAPK activity and mt transcription in mutants for the TPK1, TPK2, and TPK3 genes, which encode catalytic subunits of cytoplasmic cAPK. Protein extracts from purified mitochondria from each of the three possible double TPK mutants show mt cAMP-dependent protein phosphorylation. Relative mt transcript levels in these mutants, however, suggest that TPK2 functions less well than does TPK1 or TPK3 in organellar transcriptional control. Thus, both mt and cytoplasmic cAPKs employ the same species of regulatory and catalytic proteins, and versions of the enzyme having various combinations of catalytic species function differentially in cAMP-dependent mt transcriptional control.
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PMID:Nature and transcriptional role of catalytic subunits of yeast mitochondrial cAMP-dependent protein kinase. 782 97


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