Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Preparation of milligram amounts of [32P]p42mapk, phosphorylated at Tyr185 or diphosphorylated at Tyr185/Thr183, for use as specific protein phosphatase substrates is described. Tyr- but not Thr-phosphorylated p42mapk, accumulates when ATP is limiting. Furthermore, Tyr185-phosphorylated p42mapk exhibits an apparent 10-fold decrease in apparent Km (46.6 +/- 6.6 nM) for MAP kinase kinase compared to that for the dephospho form (approximately 476 nM). We conclude that Tyr185 precedes Thr183 phosphorylation, and that this is prerequisite, dramatically increasing the affinity of p42mapk for MAP kinase kinase.
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PMID:Ordered phosphorylation of p42mapk by MAP kinase kinase. 162 39

pp54 microtubule-associated protein-2 (MAP-2) kinase, a recently discovered protein serine/threonine kinase (Kyriakis, J., and Avruch, J. (1990) J. Biol. Chem. 265, 17355-17363), is shown to contain immunoreactive phosphotyrosine residues. Treatment with recombinant rat brain protein tyrosine phosphatase-1 deactivates pp54 MAP-2 kinase, concomitant with the removal of phosphotyrosine residues. Protein (serine/threonine) phosphatase-1 also deactivates pp54 MAP-2 kinase in a specific fashion. pp54 MAP-2 kinase joins pp42 MAP-2 kinase and cdc2/maturation-promoting factor as one of only three serine/threonine protein kinases known to be regulated by phosphorylation at both tyrosine and, independently, at serine/threonine residues. In view of these shared regulatory properties, a role for pp54 MAP-2 kinase in the control of cell division is likely.
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PMID:pp54 microtubule-associated protein-2 kinase requires both tyrosine and serine/threonine phosphorylation for activity. 164 34

Threonine and tyrosine residue phosphorylation of a 42 kDa protein identified as mitogen-activated protein kinase (MAP kinase) was stimulated in extracts from TPA-pretreated cells. It is further shown that TPA pretreatment leads to the enhancement of an activity that will induce reactivation of dephosphorylated/inactivated MAP kinase. This TPA-induced activity induces the threonine and tyrosine phosphorylation of p42 in extracts from unstimulated cells.
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PMID:TPA-induced activation of MAP kinase. 165 37

Mitogen-activated protein kinase (p42mapk) becomes transiently activated after treatment of serum-starved murine Swiss 3T3 cells or EL4 thymocytes with a diversity of mitogens. Similarly, a meiosis-activated protein kinase (p44mpk) becomes stimulated during maturation of sea star oocytes induced by 1-methyladenine. Both p42mapk and p44mpk have been identified as protein-serine/threonine kinases that are activated as a consequence of their phosphorylation. Because homologous protein kinases may play essential roles in both mitogenesis and oogenesis, we have compared in detail the biochemical properties of these two kinases. We find that these kinases are highly related based on their in vitro substrate specificities, sensitivity to inhibitors, and immunological cross-reactivity. However, they differ in apparent molecular weight and can be separated chromatographically, indicating that the two enzymes are distinct. Furthermore, in the course of this investigation, we have identified a 44-kDa protein kinase in mitogen-stimulated Swiss mouse 3T3 cells and EL4 thymocytes that co-purifies with p44mpk and thus appears to be a closer homolog of the sea star enzyme. Analysis of these protein kinases clarifies the relationships between a set of tyrosine-phosphorylated 41-45-kDa proteins present in mitogen-stimulated cells (Martinez, R., Nakamura., K. D., and Weber, M. J. (1982) Mol. Cell. Biol. 2, 653-655; Cooper, J. A., and Hunter, T. (1984) Mol. Cell. Biol. 4, 30-37), two myelin basic protein kinases identified in epidermal growth factor-treated Swiss mouse 3T3 cells (Ahn, N. G., Weiel, J. E., Chan, C. P., and Krebs, E. G. (1990) J. Biol. Chem. 265, 11487-11494), and p42mapk. Our work points to the existence of a group of related serine/threonine protein kinases, regulated by tyrosine phosphorylation and functioning at different stages of the cell cycle.
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PMID:Biochemical characterization of a family of serine/threonine protein kinases regulated by tyrosine and serine/threonine phosphorylations. 165 19

In this study we describe the activation of a protein kinase which phosphorylates a peptide, T669, comprising amino acids 663-681 of the epidermal growth factor receptor and containing the phosphate acceptor site Pro-Leu-Thr669-Pro. In the human epidermoid carcinoma cell line KB, T669 kinase activity in cytosolic extracts peaked (up to 15-fold compared with basal levels) 15-30 min after addition of interleukin-1 (IL-1) and closely paralleled receptor occupancy with a half-maximally effective concentration of approximately 100 pM IL-1 alpha. IL-1 treatment elevated T669 kinase activity to a variable extent in selected fibroblast lines, the hepatoma cell line HepG2, and the murine thymoma EL4 6.1. An IL-1 receptor-negative EL4 variant and the B cell lines 70Z/3, CB23, and RPMI 1788 did not respond in this way. All of the cell lines except 70Z/3 showed increased levels of T669 kinase when treated with the protein kinase C activator phorbol myristate acetate and/or with epidermal growth factor. This finding is in agreement with a previous study (Countaway, J. L., Northwood, I. C., and Davis, R. J. (1989) J. Biol. Chem. 264, 10828-10835). Activators of protein kinase A did not mimic the ability of IL-1 to stimulate T669 kinase activity, nor did the protein kinase C inhibitor staurosporine abrogate the effect of IL-1. T669 kinase activity from IL-1-stimulated KB cells was partially purified by ion exchange, hydrophobic interaction, and size exclusion chromatography. The partially purified enzyme phosphorylated myelin basic protein, a characteristic substrate of microtubule-associated protein-2 kinase (MAP-2 kinase) and the peptide Arg-Arg-Arg-(Tyr-Ser-Pro-Thr-Ser-Pro-Ser)4 from RNA polymerase II. Western blotting of chromatographic fractions revealed that T669 kinase activity corresponded with two proteins of 43 and 45 kilodaltons which cross-reacted with antibodies raised against peptide sequences of rat extracellular signal-regulated kinase-1/microtubule-associated protein-2 kinase. T669 kinase activity was critically dependent on the presence of phosphatase inhibitors. Since both the 43- and 45-kDa proteins, immunoprecipitated from [32P]phosphate-labeled cells, demonstrated a dramatic increase in their levels of serine, threonine, and tyrosine phosphorylation after brief treatment with IL-1, we conclude that IL-1 modulates the activity of these extracellular signal-regulated kinase/microtubule-associated protein-2 kinases by altering the level of their phosphorylation.
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PMID:Interleukin-1 represents a new modality for the activation of extracellular signal-regulated kinases/microtubule-associated protein-2 kinases. 165 5

Treatment of normal human fibroblasts with epidermal growth factor (EGF) results in the rapid (0.5 min) and simultaneous tyrosine phosphorylation of the EGF receptor (EGFr) and several other proteins. An exception to this tyrosine phosphorylation wave was a protein (42 kDa) that became phosphorylated on tyrosine only after a short lag time (5 min). We identified this p42 kDa substrate as the microtubule-associated protein (MAP) kinase using a monoclonal antibody to a peptide corresponding to the C-terminus of the predicted protein (Science 249, 64-67, 1990). EGF treatment of human fibroblasts at 37 degrees C for 5 min resulted in the tyrosine phosphorylation of 60-70% of MAP kinase as determined by the percent that was immunoprecipitated with antiphosphotyrosine antibodies. Like other tyrosine kinase growth factor receptors, the EGFr is activated and phosphorylated at 4 degrees C but is not internalized. Whereas most other substrates were readily tyrosine phosphorylated at 4 degrees C, MAP kinase was not. When cells were first stimulated with EGF at 4 degrees C and then warmed to 37 degrees C without EGF, tyrosine phosphorylation of MAP kinase was again observed. Treatment of cells with the protein kinase C activator phorbol myristate acetate (PMA) also resulted in the tyrosine phosphorylation of MAP kinase, and again only at 37 degrees C. Tryptic phosphopeptide maps demonstrated that EGF and PMA both induced the phosphorylation of the same peptide on tyrosine and threonine. This temperature and PMA sensitivity distinguishes MAP kinase from most other tyrosine kinase substrates in activated human fibroblasts.
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PMID:Temperature-dependent tyrosine phosphorylation of microtubule-associated protein kinase in epidermal growth factor-stimulated human fibroblasts. 166 89

Maturation-activated protein-serine/threonine kinases were investigated in the high-speed supernatant fractions from sea-star oocytes harvested at the time of germinal vesicle breakdown. One of the major stimulated protein kinases able to phosphorylate acetyl-CoA carboxylase in these extracts was found to co-purify with a 44 kDa myelin basic protein kinase (p44mpk) that is activated with a similar time course during oocyte maturation. Purified sea-star oocyte p44mpk phosphorylated acetyl-CoA carboxylase (purified from rat liver) predominantly on serine and to a small extent on threonine. Furthermore, the phosphorylation of acetyl-CoA carboxylase occurred principally on a tryptic phosphopeptide which displayed electrophoretic and chromatographic properties very similar to those of the peptide that has previously been shown to undergo increased phosphorylation in response to insulin in rat adipocytes [Brownsey & Denton (1982) Biochem. J. 202, 77-86]. The acetyl-CoA carboxylase was phosphorylated at a similar rate and to a similar extent by casein kinase II, which was also purified from maturing sea-star oocytes. Although casein kinase II was also activated approximately 3-fold near the time of nuclear envelope breakdown, it was responsible for only a minor component of the total enhanced acetyl-CoA carboxylase kinase activity measured in the soluble extracts from maturing oocytes. Acetyl-CoA carboxylase was a relatively poor substrate for the major S6 peptide kinase activity that was also stimulated during resumption of meiosis in the oocytes. The properties of the p44mpk are reminiscent of those of a microtubule-associated protein 2 (MAP-2) kinase that is activated in response to insulin and other mitogens in mammalian cells [Ray & Sturgill (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 3753-3757; Hoshi, Nishida & Sakai (1988) J. Biol. Chem. 263, 5396-5401]. It is intriguing that several of the mammalian protein kinases that are acutely activated after mitogenic prompting of quiescent mouse fibroblasts (i.e. G0 to G1 transition), such as MAP-2 kinase, casein kinase II and S6 kinase II, have counterparts that are activated during M-phase in maturing sea star oocytes.
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PMID:Identification of a major maturation-activated acetyl-CoA carboxylase kinase in sea star oocytes as p44mpk. 167 14

Myelin basic protein serves as a convenient substrate for detection of a 44 kDa protein-serine/threonine kinase (p44mpk) that is activated near the time of germinal vesicle breakdown in maturing echinoderm and amphibian oocytes. In vitro phosphorylation by purified p44mpk from sea star oocytes was primarily on threonine residues on a single tryptic peptide of bovine brain myelin basic protein. Amino acid composition analysis of the isolated posphopeptide revealed that it was rich in proline residues. Automated solid-phase sequencing by Edman degradation identified the major site as Thr-97 in the sequence NIVTPRTPPPSQGK, which corresponds to residues 91-104 in bovine brain myelin basic protein. Thr-94 was also phosphorylated by p44mpk to a very minor extent.
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PMID:Identification of the sites in myelin basic protein that are phosphorylated by meiosis-activated protein kinase p44mpk. 169 9

Bovine myelin basic protein (MBP) was found to be an excellent in vitro substrate (apparent Km = 50 microM) for MAP (mitogen-activated protein) kinase and can be used in lieu of microtubule-associated protein 2 for purification and functional studies of the enzyme. MBP phosphotransferase activity co-purified with MAP kinase during sequential DE52, phenyl-Superose, and gel filtration chromatography, and kinase activities for the two substrates were co-regulated by mitogen stimulation. MAP kinase phosphorylated MBP exclusively on threonine, and only one major phosphopeptide was generated by digestion with trypsin or endoproteinase Lys-C. Using mass spectrometry, we determined that the phosphorylation site is threonine 97, present in the conserved triproline loop of MBP, with (partial) sequence -Thr-Pro-Arg-Thr97-Pro-Pro-Pro-. Thr97 is a known in vivo phosphorylation site in MBP although enzymes capable of phosphorylating this site have not been identified previously. MAP kinase phosphorylated peptide 88-109 from rabbit MBP and a synthetic peptide 91-109 from human MBP but did not phosphorylate either the histone H1 peptide, utilized by p34cdc2, or the peptide substrate for the recently described proline-directed kinase. Thus, the sequence surrounding threonine 97 in bovine MBP may contain essential features of a recognition sequence for MAP kinase.
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PMID:Identification by mass spectrometry of threonine 97 in bovine myelin basic protein as a specific phosphorylation site for mitogen-activated protein kinase. 170 Sep 79

Recent studies have identified protein tyrosine phosphorylation as a major intracellular signaling pathway. However, little is known about regulation of this signaling pathway in neuronal systems. To help identify changes in levels of protein tyrosine phosphorylation in brain, we have utilized specific anti-phosphotyrosine antibodies to detect phosphotyrosine-containing proteins by immunoblotting techniques. We have found that electroconvulsive treatment induces a selective increase in tyrosine phosphorylation of a soluble 40-kDa protein. The rise is rapid and transient, reaching maximal levels at 1-2 min and returning to basal levels by 8 min. The phosphotyrosine-containing 40-kDa protein is most prominent in hippocampus, smaller in neocortex, and not detected in brainstem or cerebellum. A phosphotyrosine-containing 42-kDa protein present in several cell types has recently been identified as a serine/threonine phosphotransferase, referred to as microtubule-associated protein 2 kinase. Comparison of the levels of tyrosine phosphorylation of the 40-kDa protein and microtubule-associated protein 2 kinase activity during column chromatography of hippocampal extracts demonstrates that the phosphotyrosine-containing 40-kDa protein and microtubule-associated protein 2 co-purify. Moreover, the tyrosine phosphorylation of the 40-kDa protein and microtubule-associated protein 2 kinase activity are increased to a similar extent following electroconvulsive treatment. These findings suggest that the phosphotyrosine-containing 40-kDa protein identified in brain is closely related to microtubule-associated protein 2 kinase.
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PMID:Electroconvulsive treatment induces a rapid and transient increase in tyrosine phosphorylation of a 40-kilodalton protein associated with microtubule-associated protein 2 kinase activity. 170 29


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