Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies from this laboratory have demonstrated that arylsulfatase B (ASB) is phosphorylated by a protein kinase, which is the first finding of phosphorylation in lysosomal hydrolases. The present study was undertaken to characterize the sites of phosphorylation in ASB from transplanted human lung cancer and from normal human tissues, and to identify type of tumor protein kinase responsible for the phosphorylation of ASB. When ASB purified from liver and placenta was phosphorylated in vitro by a cAMP-dependent protein kinase, it gave a single tryptic phosphopeptide (X) and phosphothreonine. On the other hand, the tumor ASB which had been phosphorylated in vivo demonstrated two phosphopeptides X and Y. Since the tumor ASB had been shown to be phosphorylated both at threonine and serine residues, phosphorylation at threonine residue of peptide X, which is phosphorylated by a cAMP-dependent protein kinase, will be cancer-associated. Through photoaffinity labeling with a labeled cAMP analogue to detect regulatory subunits of cAMP-dependent protein kinase subtypes, it was found that the cAMP-dependent protein kinase in the transplanted lung tumor was largely type II which can be ascribed to the appearance of highly phosphorylated ASB in the tumor.
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PMID:Protein phosphorylation of human lysosomal arylsulfatase B from normal and cancer tissues. 338 98

The structure of the inhibitory domain of the inhibitor protein of the cAMP-dependent protein kinase has been assessed by circular dichroism studies of synthetic inhibitory peptides. Using the inhibitory peptide PKI(5-22)amide (Thr5-Thr-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn- Ala-Ile22) [Cheng, H.-C., Kemp, B. E., Pearson, R. B., Smith, A. J., Misconi, L., Van Patten, S. M., & Walsh, D. A. (1986) J. Biol. Chem. 261, 989-992] and shorter peptides of this sequence, it has been estimated that this parent peptide is composed of approximately 30% alpha-helix with the remainder being random coil with one beta-turn. The pseudosubstrate arginine cluster (Arg15-Arg19) is within the suggested region of random coil and beta-turn, representing one critical region of binding recognition by the protein kinase. The alpha-helix region proposed between Thr6 and Ile11 likewise contributes to the full biological potency and specificity of the inhibitor peptide and inhibitor protein. The removal of the two N-terminal threonines, for example, causes both a marked conformational change in the peptide and a diminishment by an order of magnitude of inhibitory activity. It is proposed that this alpha-helix region could serve one of several possibilities, including that it may provide a suitable constraint on the Tyr7 such that the hydroxyl is oriented in a position proximal to the pseudosubstrate domain, and/or may allow the optimal location of other protein kinase recognition signals. These data provide an initial description of some of the structural features of the inhibitor protein that could contribute to its high biological potency.
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PMID:Circular dichroic investigations of secondary structure in synthetic peptide inhibitors of cAMP-dependent protein kinase: a model for inhibitory potential. 342 97

The amino acid sequence of the heat-stable inhibitor of the cAMP-dependent protein kinase (PKI) was determined recently [Scott, J. D., Fischer, E. H., Takio, K., Demaille, J. G. & Krebs, E. G. (1985) Proc. Natl. Acad. Sci. USA 82, 5732-5736]. An earlier report [Scott, J. D., Fischer, E.H., Demaille, J. G. & Krebs, E. G. (1985) Proc. Natl. Acad. Sci. USA 82, 4379-4383] showed that at least part of the inhibitory domain of PKI is located in a 20-residue segment extending from residue 11 to residue 30: Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-Ile-His-Asp-Ile-Leu-Val-Ser- Ser-Ala . In the present study, we further mapped the inhibitory region of PKI by addition or deletion of residues at both ends of this peptide and by substitutions for specific amino acids. The results show that (i) deletion of residues 25-30 did not change inhibitory activity but addition of residues toward the amino terminus increased the inhibitory potency up to 150-fold (Ki 4.8 nM), to a level approaching that of PKI; (ii) replacement of alanine-21 by serine converted the inhibitor into a substrate having a relatively low affinity (Km 280 microM) for the enzyme; (iii) replacement of alanine-21 by phosphoserine or alpha-aminobutyric acid decreased inhibitory activity by a factor of 120 and 20, respectively; (iv) replacement of serine-13 had essentially no effect, whereas substitution of threonine-16 decreased inhibitory activity. The greatest decreases of inhibitory potency occurred with replacements of the arginines in positions 18 and 19.
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PMID:Primary-structure requirements for inhibition by the heat-stable inhibitor of the cAMP-dependent protein kinase. 345 5

Purified RNA polymerase II from chicken leukemia cells was found to be an effective substrate for protein kinase C but not cAMP-dependent protein kinase. Protein kinase C catalyzed the incorporation of 1-2 mol of phosphate per mol of polymerase II and the reaction was totally calcium and lipid dependent. Electrophoresis studies revealed a time-dependent increase of phosphate incorporation into RNA polymerase II subunits of 220 KDa, 180 KDa and 150 KDa, with a preferential phosphorylation of the 180 KDa polypeptide. The phosphorylated enzyme has a preference for using single-stranded DNA as the template for transcription, including transcription of the single-stranded myb oncogene sequence. Phosphoamino acid analysis indicated that both serine and threonine residues were phosphorylated at equal amounts. Phosphorylation by protein kinase C increased the affinity of substrate-polymerase binding and the initial rate of RNA synthesis, suggesting a mechanism by which gene expression can be activated by protein kinase C.
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PMID:Protein kinase C phosphorylates leukemia RNA polymerase II. 347 67

We have used oligonucleotide probes, based on a portion of the p60v-src autophosphorylation sequence, Glu-Asp-Asn-Glu-Tyr-Thr, to identify and characterize a cDNA from the human T-leukemia cell line, JURKAT. The JURKAT cDNA (designated ptk-JURKAT) was homologous to but distinct from the src, yes and fgr oncogenes, which encode protein-tyrosine kinases (ATP:protein phosphotransferase, EC 2.7.1.37). The ptk-JURKAT cDNA hybridized with a 2.2 kb RNA transcript from JURKAT cells and the human T-cell lymphoma line, MOLT-4, but failed to identify any transcript in two human B-cell lymphoma lines or a human erythroid-myeloid leukemia line, K562. Recently the nucleotide sequence has been established for the murine lymphocyte protein tyrosine kinase, p56LSTRA. The ptk-JURKAT cDNA appears to encode the human homolog of p56LSTRA.
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PMID:Human T lymphocytes express a protein-tyrosine kinase homologous to p56LSTRA. 348 86

As an important new reagent for studying the cAMP-dependent protein kinase, a 20-residue peptide has been synthesized that corresponds to the active site of the skeletal muscle inhibitor protein. This synthetic peptide inhibits the protein kinase competitively with a Ki = 2.3 nM; its sequence, Thr-Thr-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr- Gly-Arg-Arg-Asn-Ala-Ile-His-Asp, is that of a peptide previously reported by us which was derived from the native inhibitor protein by V8 protease digestion (Cheng, H. C., Van Patten, S. M., Smith, A. J., and Walsh, D. A. (1985) Biochem. J. 231, 655-661). Studies with analogues of this peptide show that its high affinity binding to the protein kinase (as also of the inhibitor protein) appears to be due to it mimicking the protein substrate by binding to the catalytic site via the arginine-cluster basic subsite (Formula: see text), and also to a critical contribution from one or more of the 6 N-terminal residues (Formula: see text). The availability of this high affinity synthetic peptide should open up a variety of avenues to probe the cellular actions of cAMP.
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PMID:A potent synthetic peptide inhibitor of the cAMP-dependent protein kinase. 351 Oct 44

Recent genetic and biochemical studies of two mutants of the cAMP pathway in yeast, cyr1 and bcy1, have demonstrated that cAMP-dependent protein phosphorylation plays a major regulatory role in the control of proliferation and differentiation. As a first step in examining this regulatory system in more detail and in identifying the protein substrates of cAMP-dependent protein kinase, we have analyzed phosphoprotein patterns in the mutants cyr1-2(ts) and bcy1 by two-dimensional polyacrylamide gel electrophoresis. Our analysis has revealed several proteins whose phosphorylation is controlled positively or negatively by the cAMP pathway in yeast. The presence of some of these phosphoproteins was directly associated with proliferation (positive regulation), while that of others was correlated with cell cycle arrest (negative regulation). The phosphoprotein patterns of cyr1-2(ts) temperature-arrested cells, and nitrogen (NH+4)-starved cells, were strikingly similar, suggesting that response to NH+4 is mediated in part by adenylate cyclase. Phosphoproteins whose presence correlated with cell cycle arrest were found to be phosphorylated on serine and threonine residues, while the major phosphoproteins present predominantly in proliferating cells were phosphorylated only on serine residues. None of the greater than 20 phosphoproteins we examined contained phosphotyrosine under either growth condition.
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PMID:Identification of phosphoproteins correlated with proliferation and cell cycle arrest in Saccharomyces cerevisiae: positive and negative regulation by cAMP-dependent protein kinase. 352 46

Many lysosomal hydrolases in cases of human cancer were found to be accompanied by acidic variant forms together with the major hydrolase components. Such variants were found to be phosphorylated not only at their carbohydrate moiety which contributes largely to their acidic property, but also at the protein moiety. We identified a cAMP-dependent protein kinase which is responsible for phosphorylation of arylsulfatase B. The protein kinase activity toward the sulfatase was considerably higher in transplanted lung cancer than in normal lung in the presence of cAMP. The B enzyme purified from normal human liver was found to contain 0.6mol of Pi/mol of B enzyme, and protein kinase treatment added a further 1.3mol Pi to give a single phosphopeptide (X) containing phosphothreonine. On the other hand, the B1 enzyme purified from transplanted human lung cancer which had been labeled in vivo with [32P] Pi revealed at least two phosphopeptides (X and Y). Assuming that the sulfatase from liver and lung cancer possesses the same number of available phosphorylation sites, phosphorylation of site X (Thr) which is available only by deliberate phosphorylation of the native, ordinary B enzyme, appears to be cancer-associated. Increased phosphorylation of the sulfatase resulted in a maximum 50% elevation in arylsulfatase activity, followed by a decrease in the activity upon overphosphorylation, using an artificial substrate.
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PMID:[Phosphorylation of lysosomal hydrolases in human cancer and its significance]. 360 35

The phosphorylation state of six cytoplasmic proteins is increased following treatment of isolated rat hepatocytes with hormones that elevate free intracellular Ca2+ levels (Garrison, J. C. and Wagner, J. D. (1982) J. Biol. Chem. 257, 13135-13143). Tryptic 32P-phosphopeptide maps of two of the substrates, pyruvate kinase and a 49,000-dalton protein, the major 32P-labeled protein in hepatocytes, were prepared following stimulation of cells with vasopressin, a Ca2+-linked hormone. Peptide maps of the 49,000-dalton protein phosphorylated in vitro with the recently identified multifunctional Ca2+/calmodulin-dependent protein kinase contained phosphopeptides identical to those observed in the intact cell, suggesting that this kinase is activated in response to Ca2+-mobilizing hormones. Similar in vitro phosphorylation experiments with pyruvate kinase suggested that the Ca2+/calmodulin-dependent protein kinase can phosphorylate not only the serine residues observed following vasopressin stimulation of the intact cell but also additional threonine residues. Both pyruvate kinase and the 49,000-dalton protein are also phosphorylated in the hepatocyte in response to glucagon and in vitro by the cAMP-dependent protein kinase. Both vasopressin and glucagon appear to stimulate the phosphorylation of identical serine residues in pyruvate kinase but only vasopressin enhances the phosphorylation of certain sites in the 49,000-dalton protein. Comparison of the tryptic phosphopeptide maps of these substrates phosphorylated in vitro with either the Ca2+/calmodulin-dependent protein kinase or the cAMP-dependent protein kinase suggests that the Ca2+-dependent kinase can phosphorylate unique sites in both substrates. It appears to share specificity at other sites with the cAMP-dependent protein kinase. Overall, the results suggest that the multifunctional Ca2+/calmodulin-dependent protein kinase plays an important role in the response of the hepatocyte to a Ca2+ signal.
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PMID:Evidence for the activation of the multifunctional Ca2+/calmodulin-dependent protein kinase in response to hormones that increase intracellular Ca2+. 361 Oct 57

Turkey gizzard smooth muscle myosin light chain kinase is a calmodulin-dependent enzyme containing 2 serine residues that can be phosphorylated by cAMP-dependent protein kinase. One of these sites can be phosphorylated only when calmodulin is not bound to the enzyme; the amino acid sequence around this site has been reported recently (Lukas, T. J., Burgess, W. H., Prendergast, F. G., Lau, W., and Watterson, D. M. (1986) Biochemistry 25, 1458-1464). Here we report the sequence around the site that is phosphorylated by cAMP-dependent protein kinase whether or not calmodulin is bound: Lys-Ala-Ser(P)-Gly-Ser-Ser-Pro-Thr-Ser-Pro-Ile-Asn-Ala-Asp-Lys-Val-Glu-A sn-Glu- . This sequence conforms to the previously defined criteria for substrates of cAMP-dependent protein kinase.
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PMID:Smooth muscle myosin light chain kinase. Amino acid sequence at the site phosphorylated by adenosine cyclic 3',5'-phosphate-dependent protein kinase whether or not calmodulin is bound. 378 23


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