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)

In a previous study, protein kinase FA/glycogen synthase kinase-3 (FA/GSK-3) was identified as a myelin basic protein (MBP) kinase associated with intact brain myelin. In this report, the phosphorylation sites of MBP by kinase FA/GSK-3 were further determined by two-dimensional electrophoresis/TLC, phosphoamino acid analysis, tryptic peptide mapping, Edman degradation, and direct sequencing. Kinase FA/GSK-3 phosphorylates MBP on both threonine and serine residues. Three tryptic phosphopeptide peaks were resolved by C18 reverse-phase HPLC. Sequential manual Edman degradation together with direct sequence analysis revealed that T(p)PPPSQGK is the phosphorylation site sequence for the first major phosphopeptide peak. When mapping with the bovine brain MBP sequence, we finally demonstrate Thr97-Pro, one of the in vivo phosphorylation sites in MBP, as the major site phosphorylated by kinase FA/GSK-3, implicating a physiologically relevant role of FA/GSK-3 in the regulation of brain myelin function. By using the same approach, we also identified NIVT94(p)PR as the phosphorylation site sequence in the second major tryptic phosphopeptide derived from [32P]MBP phosphorylated by kinase FA/GSK-3, further indicating that kinase FA/GSK-3 represents a Thr-Pro motif-directed MBP kinase involved in the phosphorylation of brain myelin.
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PMID:Protein kinase FA/glycogen synthase kinase-3 predominantly phosphorylates the in vivo site Thr97-Pro in brain myelin basic protein: evidence for Thr-Pro and Ser-Arg-X-X-Ser as consensus sequence motifs. 751 Jul 85

The enzyme glycogen synthase kinase-3 (GSK-3) has been implicated in the control of several metabolic enzymes and transcription factors in response to extracellular signals. In the past, the enzyme has been considered to be a protein Ser/Thr kinase although it was recently reported to contain Tyr(P) (Hughes, K., Nikolakaki, E., Plyte, S. E., Totty, N. F., and Woodgett, J. R. (1993) EMBO J. 12, 803-808). A cDNA encoding rabbit skeletal muscle GSK-3 beta was cloned and expressed in Escherichia coli as an active protein kinase, with apparent M(r) 46,000, capable of phosphorylating several known GSK-3 substrates. Recombinant GSK-3 beta autophosphorylated on Ser, Thr, and Tyr residues although the enzyme already contained Tyr(P) as judged by its recognition by anti-Tyr(P) antibodies. The net result of the autophosphorylation was a 3-5-fold reduction in enzyme activity. GSK-3 alpha, purified from rabbit muscle, also underwent autophosphorylation but only on Ser and Thr residues. In this case, the autophosphorylation stabilized the enzyme activity compared with the control lacking ATP/Mg2+. Of several phosphatases tested, the lambda-phage phosphatase was the most effective in dephosphorylating at Ser and Thr residues but did not dephosphorylate at Tyr residues. The action of the lambda-phosphatase caused a reactivation of GSK-3 beta to approximately 80% of the starting activity. The protein tyrosine phosphatase PTP1B was able to dephosphorylate at Tyr residues leading to a reduction in enzyme activity. A truncated form of GSK-3 beta, apparent M(r) 40,000, had a significantly higher specific activity, was defective in autophosphorylation, and was not inactivated in the autophosphorylation reaction. We conclude that GSK-3 beta is a dual specificity protein kinase in the same sense as the mitogen-activated protein kinase/ERK family of enzymes. Phosphorylation at different residues differentially controls enzyme activity, Ser/Thr phosphorylation causing inactivation and Tyr phosphorylation resulting in increased activity.
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PMID:Glycogen synthase kinase-3 beta is a dual specificity kinase differentially regulated by tyrosine and serine/threonine phosphorylation. 751 73

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

Spleen TPK-IIB is an acidophilic protein tyrosine kinase, devoid of autophosphorylation activity, whose phosphorylation of the src-peptide NEYTA is crucially specified by Glu-2[(1991) J. Biol. Chem. 266, 17798-17803]. We show that phosphothreonine, phosphotyrosine and phosphoserine are, in this order, specificity determinants even more effective than glutamic acid if they are replacing Glu-2, to give the phosphopeptides NTpYTA, NYpYTA, NSpYTA, respectively. Non-phosphorylated threonine, tyrosine and serine are conversely ineffective. Consequently also the heptapeptide GEGTYGV reproducing the phosphoacceptor and inhibitory site of p34cdc2 is not appreciably affected by TPK-IIB, unless its threonyl residue is previously phosphorylated, the phosphoderivative GEGTpYGV being readily phosphorylated at its tyrosyl residue. Such a behaviour is unique for TPK-IIB among the protein tyrosine kinases tested (lyn-TPK, fgr-TPK and EGF-receptor, besides TPK-IIB). These data provide the first evidence that, in some instances, the targeting by protein tyrosine kinases can be specifically determined by the previous phosphorylation of the peptide substrate, thus extending the concept of 'hierarchal phosphorylation' [(1991) J. Biol. Chem. 266, 14139-14142] to tyrosyl residues as well.
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PMID:Phosphorylated residues as specificity determinants for an acidophilic protein tyrosine kinase. A study with src and cdc2 derived phosphopeptides. 768 79

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

We report here the isolation of the Arabidopsis thaliana gene AtK-1. The predicted protein sequence of AtK-1 shows 70% identity to the Arabidopsis ASK and alfalfa MsK kinases that are homologs of the Drosophila shaggy and rat GSK-3 serine/threonine protein kinases playing an important role in signal transduction processes in animals. Northern analysis of different organs revealed exclusive expression in inflorescences suggesting an involvement of the AtK-1 kinase in reproduction-specific processes.
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PMID:Inflorescence-specific expression of AtK-1, a novel Arabidopsis thaliana homologue of shaggy/glycogen synthase kinase-3. 786 93

Inhibitor-2 (I-2) inhibits the free catalytic subunit of type 1 phosphatase (CS1) and controls the cyclic inactivation/activation of CS1 in the ATP-Mg-dependent protein phosphatase complex. We report here the effect of mutations on these two properties of I-2. Substitution of Thr-72 with Ala, Asp, or Glu generated complexes with CS1 that could not be activated. Mutation of Ser-86 did not affect activation by glycogen synthase kinase-3 (GSK-3) alone but impaired synergistic activation by casein kinase II and GSK-3. Mutations in the region between Thr-72 and Ser-86 did not alter the inhibitory potency of I-2 but prevented complete inactivation of CS1. A mutant without the 35 NH2-terminal residues exhibited an IC50 for CS1 200-fold higher than that of wild-type I-2. However, it formed an inactive phosphatase complex with CS1, which was activated by GSK-3. A mutant with the 59 COOH-terminal residues deleted retained full inhibitory activity and formed an inactive complex that could not be activated by GSK-3. We conclude that the NH2-terminal region of I-2 is involved in inhibition, that the sequence between Thr-72 and Ser-86 is necessary for the conversion of CS1 from an active to an inactive conformation, and that the COOH terminus is required for activation by GSK-3. Thus, different functional domains of I-2 may interact with distinct regions of CS1.
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PMID:Domains of phosphatase inhibitor-2 involved in the control of the ATP-Mg-dependent protein phosphatase. 796 54

To identify consensus sequence motif for a new family of protein kinase termed autophosphorylation-dependent protein serine/threonine kinase (auto-kinase), we have tested several synthetic peptides. The well established protein serine/threonine kinases such as cAMP-dependent protein kinase, Ca2+/calmodulin-dependent protein kinase (CaM-kinase), and protein kinase C were found to be inactive toward phosphorylation of syntide-3 (RPRPASVPPSPSLSRHA), which turned out to be an excellent substrate only for auto-kinase, indicating that syntide-3 is a specific substrate for auto-kinase. Modification of syntide-3 to become RPRPASVPPS/T did not affect the activity of auto-kinase. By contrast, autokinase became rather or almost inactive when the peptide was modified to become RPRPASVPPA/G/F/K/R/D/E/Y, indicating that amino acid number 10 in syntide-3 is crucial to the sequence motif recognized by auto-kinase. Phosphorylation of myelin basic protein (MBP) by autokinase revealed that auto-kinase predominantly phosphorylates MBP on one particular site with RT-T(p)HYGS as the phosphorylation site sequence, which could not be phosphorylated by any other reported MBP kinases including cAMP-dependent protein kinase, CaM-kinase, protein kinase C, mitogen-activated protein kinase, and kinase FA/GSK-3. Taken together, the results provide initial evidence that -Arg-X-(X)-Ser/Thr-X3-Ser/Thr- may represent a unique consensus sequence motif specifically recognized by autophosphorylation-dependent protein kinase, a new family of multi-substrate/multifunctional protein serine/threonine kinase.
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PMID:Identification of -R-X-(X)-S/T-X3-S/T- as consensus sequence motif for autophosphorylation-dependent protein kinase. 785 32

We report here the sequence of RPK1 (for Regulatory cell Proliferation Kinase), a new Saccharomyces cerevisiae gene coding for a protein with sequence similarities to serine/threonine protein kinases. The protein sequence of 764 amino acids includes an amino-terminal domain (residues 1-410), which may be involved in regulation of the kinase domain (residues 411-764). The catalytic domain of Rpk1 is not closely related to other known yeast protein kinases but exhibits strong homology to a newly discovered group of mammalian kinases (PYT, TTK, esk) with serine/threonine/tyrosine kinase activity. Null alleles of RPK1 are lethal and thus this gene belongs to the small group of yeast protein kinase genes that are essential for cell growth. In addition, eliminating the expression of RPK1 gives rise to the accumulation of non-viable cells with less than a 1 N DNA content suggesting that cells proceed into mitosis without completion of DNA synthesis. Therefore, the Rpk1 kinase may function in a checkpoint control which couples DNA replication to mitosis. The level of the RPK1 transcript is extremely low and constant throughout the mitotic cycle. However it is regulated during cellular differentiation, being decreased in alpha-factor-treated a cells and increased late in meiosis in a/alpha diploids. Taken together, our results suggest that Rpk1 is involved in a pathway that coordinates cell proliferation and differentiation.
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PMID:RPK1, an essential yeast protein kinase involved in the regulation of the onset of mitosis, shows homology to mammalian dual-specificity kinases. 802 80


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