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:2.7.11.24 (mitogen-activated protein kinase)
95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment of quiescent rat fibroblastic cells (3Y1) with colchicine, a microtubule-disrupting agent, which could induce the initiation of DNA synthesis [Y. Shinohara, E. Nishida, and H. Sakai (1989) Eur. J. Biochem. 183, 275-280], activated a serine/threonine-specific protein kinase activity in cell extracts that preferentially phosphorylated exogenous microtubule-associated protein 2 (MAP2). Vinblastine treatment also activated the kinase activity, and taxol pretreatment inhibited the colchicine-induced activation of this kinase activity. The detailed biochemical characterization indicated that this microtubule disruption-activated MAP2 kinase was very similar or identical to the mitogen-activated MAP kinase in the substrate specificity and chromatographic behaviors on phosphocellulose, DEAE-cellulose, gel filtration, and phenyl-Sepharose. Pretreatment of the cells with protein synthesis inhibitors did not prevent the MAP2 kinase activation by colchicine. Moreover, phosphatase treatment inactivated the colchicine-activated MAP2 kinase activity. These data suggest that microtubule disruption activates MAP kinase through phosphorylation.
...
PMID:Activation of microtubule-associated protein kinase by microtubule disruption in quiescent rat 3Y1 cells. 184 31

Growth factor activation of serine/threonine protein kinases was studied by treating quiescent Swiss 3T3 cells with epidermal growth factor (EGF) and examining cytosolic extracts for protein kinase activity under conditions inhibitory to calcium- and cyclic nucleotide-dependent kinases. Cytosolic extracts of cells stimulated for 5 min were fractionated by Mono Q fast protein liquid chromatography. Eight peaks of kinase activity were resolved, of which five were stimulated by EGF treatment of cells. These peaks were revealed using the synthetic peptide Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala (S6 peptide), 40 S ribosomal S6 protein, glycogen synthase, microtubule-associated protein 2, and myelin basic protein as substrates. The peaks varied in the kinetics of their activation by EGF and in their response to insulin. Selected peaks were resolved further by sizing gel chromatography. The results together indicate that at least seven distinct fractions of cytosolic kinase activities are stimulated in Swiss 3T3 cells by EGF. One of these, which phosphorylates both S6 protein and S6 peptide, is similar to the S6 kinase characterized previously in this cell line by others. Four additional activities that also phosphorylate the S6 protein and S6 peptide appear unrelated to this enzyme. Finally, two kinase activities that phosphorylate both myelin basic protein and microtubule associated protein 2 are EGF stimulated. One is similar to an insulin-stimulated microtubule-associated protein 2 kinase described in other cell lines whereas the other seems to represent a novel activity. Several of these EGF-stimulated activities were inactivated by protein phosphatases, suggesting that they might be regulated by phosphorylation.
...
PMID:Identification of multiple epidermal growth factor-stimulated protein serine/threonine kinases from Swiss 3T3 cells. 214 53

An hepatic protein kinase that phosphorylates microtubule-associated protein 2 (MAP-2) on Ser/Thr residues is markedly activated after intraperitoneal injection of cycloheximide in the rat. The enzyme has been purified greater than 10,000-fold to near homogeneity and corresponds to a 54-kDa polypeptide, based on auto-phosphorylation, renaturation of activity from sodium dodecyl sulfate gels, and gel filtration. The protein kinase activity is unaffected by prior autophosphorylation, Ca2+, diacylglycerol and phospholipids, cyclic nucleotides, staurosporine, and protein kinase inhibitor, but can be totally and specifically deactivated by the Ser/Thr protein phosphatase 2A. The enzyme is inhibited completely but reversible by transition metals and p-chloromercuribenzoate, and is strongly stimulated by poly-L-lysine toward most, but not all protein substrates. The activity of the cycloheximide-stimulated MAP-2 kinase (pp54 MAP-2 kinase) toward potential polypeptide substrates was compared to that of an insulin-stimulated MAP-2 kinase (pp42 MAP-2 kinase). Although both MAP-2 kinases exhibited little or no ability to phosphorylate histones and casein, the two kinases had a distinguishable substrate specificity. At comparable MAP-2 phosphorylating activities, pp42 MAP-2 kinase, but not pp54 MAP-2 kinase, phosphorylated and activated the Xenopus S6 protein kinase II. Moreover, pp42 MAP-2 kinase phosphorylated myelin basic protein at 10-12-fold higher rates than did pp54 MAP-2 kinase. Cycloheximide-activated pp54 MAP-2 protein kinase appears to be a previously uncharacterized protein kinase that is itself regulated through Ser/Thr phosphorylation and, perhaps, polypeptide regulators with basic domains. The identity of the upstream regulatory elements and the native substrates remain to be established.
...
PMID:pp54 microtubule-associated protein 2 kinase. A novel serine/threonine protein kinase regulated by phosphorylation and stimulated by poly-L-lysine. 217 Mar 74

Chymotryptic digestion was used to localize the sites in microtubule-associated protein 2 which are preferentially phosphorylated in vitro by MAP kinase, an insulin-stimulated serine/threonine kinase which efficiently utilizes high molecular weight MAPs as substrates. MAP kinase phosphorylates sites in the projection domain almost exclusively; less than 6% of the phosphate incorporated by MAP kinase was found in the tubulin binding domain. This site specificity is in marked contrast to that of the catalytic subunit of cAMP dependent protein kinase, and most other protein kinases phosphorylating MAP-2, which extensively phosphorylate the tubulin binding domain.
...
PMID:Phosphorylation of microtubule-associated protein 2 by MAP kinase primarily involves the projection domain. 254 2

pp42, a low-abundance 42-kDa protein, becomes transiently phosphorylated on tyrosine after stimulation of fibroblasts by a variety of mitogens, including epidermal growth factor, platelet-derived growth factor, phorbol 12-myristate 13-acetate, thrombin, and insulin-like growth factor II. The induction of pp42 phosphorylation on tyrosine by such diverse mitogenic agents suggests an important role for pp42 in the cascade of events necessary for cell transition from G0 into the cell cycle. However, as with most proteins identified on the basis of their tyrosine phosphorylation, the function of pp42 in cellular regulation is unknown. In this manuscript we report evidence that suggests that pp42 is a serine/threonine-specific protein kinase. Stimulation of 3T3-L1 cells with insulin has been shown to activate a cytosolic serine/threonine kinase capable of phosphorylating microtubule-associated protein 2 (MAP-2) and ribosomal protein S6 kinase II. This cytosolic serine/threonine protein kinase, which itself is phosphorylated on tyrosine, has been termed "MAP kinase". We now report that pp42 phosphorylation and MAP kinase activation occur in fibroblasts in response to similar mitogens, that the two proteins comigrate on one- and two-dimensional polyacrylamide gels, and that the two proteins copurify chromatographically. The major peptides generated from purified MAP kinase by V8 protease digestion are present as a subset of the peptides in digests of pp42 excised from two-dimensional gels. Thus, the results suggest that MAP kinase is tyrosine-phosphorylated pp42.
...
PMID:Evidence that pp42, a major tyrosine kinase target protein, is a mitogen-activated serine/threonine protein kinase. 255 Sep 26

A protein kinase, termed microtubule-associated protein (MAP) kinase, which phosphorylates microtubule-associated protein 2 (MAP-2) in vitro and is stimulated 1.5-3-fold in extracts from insulin-treated 3T3-L1 cells has been identified (Ray, L.B., and Sturgill, T.W. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 1502-1506). Here, we describe chromatographic properties of MAP kinase and provide biochemical characterization of the partially purified enzyme. Isolation of the enzyme is facilitated by its unusually high affinity for hydrophobic interaction chromatography matrices. The molecular weight of the partially purified enzyme was determined to be 35,000 by gel filtration chromatography and 37,000 by glycerol gradient centrifugation. MAP kinase activity of chromatographic fractions correlated precisely with the presence of a 40-kDa phosphoprotein detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. MAP kinase has a Km of 7 microM for ATP and does not utilize GTP. Acetyl-CoA carboxylase, ATP citrate-lyase, casein, histones, phosvitin, protamine, and ribosomal protein S6 were all poor substrates relative to MAP-2. The enzyme is inhibited by fluoride and beta-glycerol phosphate but not by heparin. These properties of MAP kinase distinguish it from protein kinases previously described in the literature.
...
PMID:Characterization of insulin-stimulated microtubule-associated protein kinase. Rapid isolation and stabilization of a novel serine/threonine kinase from 3T3-L1 cells. 284 41

Insulin treatment (Kact, 5 X 10(-9) M) of serum-starved 3T3-L1 adipocytes stimulates a soluble serine/threonine kinase that catalyzes phosphorylation of microtubule-associated protein 2 (MAP-2) in vitro. Maximal activation of MAP-2 kinase activity by 80 nM insulin was observed after 10 min of hormonal stimulation, prior to maximal stimulation of S6 kinase activity (20 min). The insulin-stimulatable MAP-2 kinase activity is not adsorbed to phosphocellulose, whereas the principal S6 kinase activity is retained and elutes at approximately 0.5 M NaCl. The insulin-stimulatable MAP-2 kinase is less stable during incubation at 30 degrees C than S6 kinase activity. Inclusion of phosphatase inhibitors decreases the rate at which the stimulated MAP-2 kinase activity is lost from extract supernatants incubated at 30 degrees C. p-Nitrophenyl phosphate is more effective than DL-phosphotyrosine, whereas DL-phosphoserine is without effect at the concentration used (40 mM). The difference in MAP-2 kinase activity in extract supernatants from control and insulin-treated cells is also preserved after rapid chromatography on Sephadex G-25. These results show that a soluble serine/threonine kinase is rapidly activated by insulin, possibly by phosphorylation of either the kinase itself or an interacting modulator.
...
PMID:Rapid stimulation by insulin of a serine/threonine kinase in 3T3-L1 adipocytes that phosphorylates microtubule-associated protein 2 in vitro. 295 32

Exposure of 3T3-L1 cells to insulin stimulates a soluble, serine(threonine)-specific protein kinase that phosphorylates microtubule-associated protein 2 (MAP-2) in vitro. The enzyme, termed MAP kinase, was isolated from insulin-treated or control cells radiolabeled with 32Pi. A 40-kDa phosphoprotein was found to elute in exact correspondence with enzymatic activity during hydrophobic interaction and gel filtration chromatography of extracts from cells stimulated with insulin. Both MAP kinase activity and the phosphoprotein were absent in fractions prepared from untreated cells. The 32P incorporated into the 40-kDa protein was stable during treatment with alkali. Phospho amino acid analysis confirmed that the radiolabel was primarily incorporated into phosphotyrosine and to a lesser extent phosphothreonine. In addition, MAP kinase was incompletely but specifically adsorbed by antibodies to phosphotyrosine. We conclude, based on these data and additional studies from this laboratory, that MAP kinase is phosphorylated on tyrosine in vivo. The data are consistent with the possibility that MAP kinase may be a substrate for the insulin receptor or another insulin-regulated tyrosine kinase.
...
PMID:Insulin-stimulated microtubule-associated protein kinase is phosphorylated on tyrosine and threonine in vivo. 328 75

In previous studies, we described a soluble Ca2+/calmodulin-dependent protein kinase which is the major Ca2+/calmodulin-dependent microtubule-associated protein 2 (MAP-2) kinase in rat brain [Schulman, H. (1984) J. Cell Biol. 99, 11-19; Kuret, J. A., & Schulman, H. (1984) Biochemistry 23, 5495-5504]. We now demonstrate that this protein kinase has broad substrate specificity. Consistent with a multifunctional role in cellular physiology, we show that in vitro the enzyme can phosphorylate numerous substrates of both neuronal and nonneuronal origin including vimentin, ribosomal protein S6, synapsin I, glycogen synthase, and myosin light chains. We have used MAP-2 to purify the enzyme from rat lung and show that the brain and lung kinases have nearly indistinguishable physical and biochemical properties. A Ca2+/calmodulin-dependent protein kinase was also detected in rat heart, rat spleen, and in the ring ganglia of the marine mollusk Aplysia californica. Partially purified MAP-2 kinase from each of these three sources displayed endogenous phosphorylation of a 54 000-dalton protein. Phosphopeptide analysis reveals a striking homology between this phosphoprotein and the 53 000-dalton autophosphorylated subunit of the major rat brain Ca2+/calmodulin-dependent protein kinase. The enzymes phosphorylated MAP-2, synapsin I, and vimentin at peptides that are identical with those phosphorylated by the rat brain kinase. This enzyme may be a multifunctional Ca2+/calmodulin-dependent protein kinase with a widespread distribution in nature which mediates some of the effects of Ca2+ on microtubules, intermediate filaments, and other cellular constituents in brain and other tissues.
...
PMID:Ca2+/calmodulin-dependent microtubule-associated protein 2 kinase: broad substrate specificity and multifunctional potential in diverse tissues. 407 98

The microtubule-associated protein 2 (MAP2) and its juvenile splicing variant MAP2c contain a phosphorylation site at Ser136 which is part of a Ser-Pro motif. This site lies within the N-terminal region common to MAP2b and MAP2c. It has been mapped by site-directed mutagenesis of recombinant MAP2c and by a monoclonal antibody AP18 whose epitope contains the phosphorylated Ser136. In vitro this site is phosphorylated by proline-directed kinases such as MAP kinase, GSK-3, or members of the cdk family, but not by other kinases such as PKA, PKC, or CaMK-II. MAP2a,b or MAP2c isolated from brain is found to be endogenously phosphorylated at Ser136. After microinjection into several cell lines dephosphorylated MAP2 isoforms or recombinant MAP2c become also phosphorylated at Ser136 in vivo. Injection of MAP2a,b or MAP2c into living cells causes reorganization of microtubules, including bundle formation. This effect is independent of the phosphorylation at Ser136. The specificity of the phosphorylation reaction provides a tool for analyzing the role and posttranslational processing of MAP2 in nerve cell development.
...
PMID:Phosphorylation of microtubule-associated proteins MAP2a,b and MAP2c at Ser136 by proline-directed kinases in vivo and in vitro. 752 90


<< Previous 1 2 3 4 5 Next >>

---