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

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of butyrate-mediated differentiation of human colon carcinoma cells on the expression of src-related tyrosine protein kinases were analyzed. The results demonstrate that treatment of a variety of colon carcinoma cell lines with 2 mM sodium butyrate resulted in diminished population doubling rates, altered morphology, decreased anchorage-independent growth, and increased expression of colon epithelial differentiation marker enzymes such as alkaline phosphatase. In butyrate-treated cells, significantly diminished protein kinase activities and abundance of pp60c-src and p56lck were found to parallel the butyrate-induced phenotypic alterations. For the lck gene, the decreased levels in p56lck abundance were found to coincide with diminished levels of steady-state lck mRNAs. In contrast, treatments which arrested the growth of the colon carcinoma cells without inducing differentiation had no effect on the level of expression of these proteins. Furthermore, colon carcinoma cell lines which were found to be resistant to butyrate-induced differentiation showed no change in the kinase activity or abundance of either protein following butyrate treatment. These results indicate that the expression of several src-related kinases in human colon carcinoma can be influenced by the differentiation state of the cells.
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PMID:Alterations in the expression of pp60c-src and p56lck associated with butyrate-induced differentiation of human colon carcinoma cells. 247 6

Total trehalose-6-phosphate synthase activity decreased in cell extracts from Candida utilis under conditions inducing activation of the regulatory trehalase by protein kinase catalysed phosphorylation. The synthase activity was reactivated by treatment with alkaline phosphatase revealing the presence of an enzyme whose activity is inactivated by reversible phosphorylation. The occurrence in the trehalose-6-phosphate synthase complex of a second synthase enzyme whose activity is not controlled by phosphorylation and dephosphorylation was demonstrated following gel filtration of cell extracts. The activity of the isolated enzymes was differently modified in vitro by the presence of alkaline phosphatase, ATP, glucose or protein kinase.
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PMID:Presence of two trehalose-6-phosphate synthase enzymes in Candida utilis. 253 27

The role of phosphorylation/dephosphorylation in the regulation of CTP:phosphocholine cytidylyltransferase activity was investigated. Incubation of post mitochondrial supernatant with cAMP-dependent protein kinase (50 units) led to an increased (28%) recovery of the cytidylyltransferase in the cytosolic fraction, while incubation with an intestinal alkaline phosphatase (20 units) led to an increased (61%) recovery in the microsomal fraction. When pure cytidylyltransferase was incubated with washed microsomes in the presence of cAMP-dependent protein kinase (133 units), the enzyme associated with the supernatant fraction increased (3.12 +/- 0.02 to 3.77 +/- 0.03 nmol/min/ml) while that of the microsomal fraction decreased (1.36 +/- 0.01 to 0.56 +/- 0.05 nmol/min/ml) by 2.5-fold. The increase in the cytidylyltransferase activity in the supernatant corresponded to an increase in 32P incorporation into the cytidylyltransferase. Treatment with alkaline phosphatase (40 units) decreased the cytidylyltransferase activity in the supernatant (3.61 +/- 0.08 to 2.88 +/- 0.07 nmol/min/ml) while the activity in the microsomal fraction increased (0.56 +/- 0.08 to 1.16 +/- 0.06 nmol/min/ml) by 2-fold. The decrease in the cytidylyltransferase activity in the supernatant corresponded to a decrease in 32P incorporation into the cytidylyltransferase. Incubation of cytidylyltransferase with phosphatidylcholine vesicles in the presence of cAMP-dependent protein kinase (110 units) decreased the cytidylyltransferase activity by 30%. The decrease in cytidylyltransferase activity corresponded to an increase in 32P incorporation into the cytidylyltransferase. Treatment with alkaline phosphatase (20 units) resulted in a 41% increase in the cytidylyltransferase activity. The increase in cytidylyltransferase activity corresponded to a decrease in 32P incorporation into the cytidylyltransferase. Incubation of the cytidylyltransferase with [gamma-32P] ATP and cAMP-dependent protein kinase led to incorporation of 32P into the serine residues of cytidylyltransferase. If the cytidylyltransferase were preincubated with alkaline phosphatase prior to incubation with cAMP-dependent protein kinase, 2-fold more 32P (0.2 mol P/mol cytidylyltransferase) was incorporated into the cytidylyltransferase. Collectively, this data is in agreement with a role for reversible phosphorylation in the regulation of cytidylyltransferase.
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PMID:CTP:phosphocholine cytidylyltransferase is a substrate for cAMP-dependent protein kinase in vitro. 253 19

Binding of epidermal growth factor (EGF) stimulates tyrosyl protein kinase activity of its receptor in the epidermis. This tyrosine residue phosphorylation is thought to be one mechanism by which EGF mediates its effects such as growth stimulation. To modulate a cellular response to EGF, an enzyme which dephosphorylates phosphotyrosyl residues should be present to oppose the effect of the tyrosyl kinase activity of the EGF receptor. We have identified an enzyme in the neonatal mouse epidermis which has the ability to dephosphorylate tyrosyl residues in vitro on EGF receptors. This phosphatase is a soluble protein with a molecular weight greater than 10,000 daltons and shows optimum activity at neutral pH. This epidermal tyrosyl protein phosphatase is not inhibited by tartrate, ATP, and micromolar levels of zinc, but is inhibited by millimolar levels of zinc, magnesium, manganese, and fluoride. Unlike other well-known phosphotyrosyl phosphatases, alkaline phosphatase, and calcineurin, this enzyme is not inhibited by EDTA. Thus, we have identified and partially characterized a possibly unique phosphotyrosyl phosphatase from the epidermis.
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PMID:Identification of a phosphotyrosyl-protein phosphatase in mouse epidermis. 253 66

We have purified and characterized two kinds of GTP-binding proteins with Mr of 22,000 in human platelet membrane (main; m22KG(I), minor; m22KG(II)) (Nagata, K. and Nozawa, Y. (1988) FEBS Lett. 238, 90-94). In this study, the main GTP-binding protein (m22KG(I)) was found to be phosphorylated by cyclic AMP-dependent protein kinase (A-kinase), but not by protein kinase C. About 0.5 mol of phosphate was maximally incorporated into one mol of the protein and this phosphorylation was inhibited in the presence of A-kinase inhibitor. Phosphorylation of m22KG(I) did not alter either its GTP-binding or GTPase activity. When m22KG(I) was incubated alone or in the presence of 100 microM guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) and then exposed to A-kinase, no significant changes in the level of phosphorylation were observed. On the other hand, the most abundant GTP-binding protein with Mr of 21,000 (c21KG) in human platelet cytosol, which was identified as a transformation suppressor gene product (rap 1 protein, smg p21 and Krev-1 protein), was not phosphorylated by A-kinase under the same condition. However, c21KG was phosphorylated by A-kinase after pretreatment with alkaline phosphatase.
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PMID:Low Mr GTP-binding proteins in human platelets: cyclic AMP-dependent protein kinase phosphorylates m22KG(I) in membrane but not c21KG in cytosol. 254 Jul 45

We have examined the potential for using calf uterine progesterone receptor (PR) as a substrate for phosphorylation by cAMP-dependent protein kinase (cAMP-PK), PR was found to interact with anti-PR monoclonal antibody alpha PR6 (Sullivan et al., 1986), which was to immunopurify the receptor. Protein staining of the purified preparation revealed the presence of two major bands corresponding to 114 kDa and 90 kDa peptides; only 114 kDa peptide could be photoaffinity-labeled with R5020. The 90 kDa peptide co-migrated with 90 kDa heat shock protein (hsp-90) precipitated by anti-hsp-90 monoclonal antibody AC88 (Riehl et al., 1985). Incubation of the immunopurified protein-A-Sepharose-adsorbed PR with the catalytic subunit of cAMP-PK in the presence of gamma-[32P]ATP and divalent cations resulted in a Mg++-dependent incorporation of 32P-radioactivity into both the 114 kDa and the hsp-90 peptides. Small 32P-incorporation was also seen in the 114 kDa peptide in the presence of Mn++. A 60 degrees C preincubation of immunopurified PR increased the extent of phosphorylation of the hsp-90 peptide. A pretreatment with alkaline phosphatase reduced the ability of PR to act as a substrate while the steroid occupancy of PR appeared to enhance the phosphorylation of the 114 kDa peptide. The differential cation requirement for the phosphorylation of 114 kDa and hsp-90 peptides and a selective hormone-dependent increase in the phosphorylation of the 114 kDa peptide suggest a possible role of phosphorylation in mediating progesterone action in the calf uterus.
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PMID:Phosphorylation of calf uterine progesterone receptor by cAMP-dependent protein kinase. 254 44

Treatment of Jurkat T-cells with anti-CD-3 monoclonal antibodies resulted in the rapid and transient activation of a serine kinase which utilized the microtubule-associated protein, MAP-2, as a substrate in vitro. The kinase was also activated on treatment of Jurkat cells with phytohaemagglutinin, but with a different time course. The activation of the MAP-2 kinase by anti-CD-3 antibodies was dose-dependent, with maximal activity observed at concentrations of greater than 500 ng/ml. Normal human E-rosette-positive T-cells also exhibited induction of MAP-2 kinase activity during anti-CD-3 treatment. The enzyme was optimally active in the presence of 2 mM-Mn2+; lower levels of activity were observed with Mg2+, even at concentrations up to 20 mM. The kinase was partially purified by passage over DE-52 Sephacel with the activity eluting as a single peak at 0.25 M-NaCl. The molecular mass was estimated to be 45 kDa by gel filtration. The activation of the MAP-2 kinase was probably due to phosphorylation of this enzyme as treatment with alkaline phosphatase diminished its activity. These data demonstrate that the stimulation of T-cells through the CD-3 complex results in the activation of a novel serine kinase which may be critically involved in signal transduction in these cells.
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PMID:Complexing of the CD-3 subunit by a monoclonal antibody activates a microtubule-associated protein 2 (MAP-2) serine kinase in Jurkat cells. 255 97

Short term regulation of hepatic cholesterol ester hydrolase by reversible phosphorylation is described. Two different kinase systems seem to be involved in this regulation. The addition of ATP, cyclic AMP and Mg2+ to rat liver 104,000 X g supernatant (S104) produced a 100-140% increase in cholesterol ester hydrolase activity. This stimulation was abolished when protein kinase inhibitor was added prior to the addition of ATP, cyclic AMP and Mg2+. Cholesterol ester hydrolase activity was also stimulated when calcium ions, phosphatidylserine, and diolein were added to S104 along with ATP and Mg2+. Diolein in this reaction could be substituted by phorbol 12-myristate 13-acetate. Preincubation of S104 with alkaline phosphatase resulted in a deactivation of cholesterol ester hydrolase. The addition of increasing concentrations of Mg2+ to S104 produced increasing inhibition of cholesterol ester hydrolase activity, and this effect was blocked by NaF. It is suggested that rat liver cholesterol ester hydrolase is activated by cyclic AMP dependent protein kinase and protein kinase C. Deactivation is accomplished by dephosphorylation catalyzed by a phosphoprotein phosphatase, dependent on Mg2+.
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PMID:Activation of rat liver cholesterol ester hydrolase by cAMP-dependent protein kinase and protein kinase C. 255 47

Stathmin is a ubiquitous soluble protein (Mr approximately 19,000, pI approximately 6.2-5.5) whose phosphorylation is associated with the intracellular mechanisms involved in the regulations of cell differentiation and functions by extracellular effectors. Its purification from rat brain and the preparation of specific antibodies allowed us to identify a set of immunologically related unphosphorylated (N1, N2) and phosphorylated (P1, P2a, P2b, P3) proteins of decreasing isoelectric points. All these proteins yielded identical silver-stained or 32P-radioactive peptide maps with the protease V8 from Staphylococcus aureus, indicating that they are also structurally related. In vitro phosphorylation with the exogenous catalytic subunit of the cAMP-dependent protein kinase, as well as dephosphorylation with alkaline phosphatase, indicated that P1, P2, and P3 derived from N1 and N2 by progressive phosphorylation. Phosphorylation of individual proteins extracted from semi-preparative two-dimensional polyacrylamide gels demonstrated the existence of two distinct isoforms of stathmin, alpha and beta: N1 and N2 are their respective unphosphorylated forms (alpha O and beta O), whereas proteins P1-P3 could be resolved as at least three increasingly phosphorylated forms of both alpha and beta stathmin (alpha 1, alpha 2, alpha(3) and beta 1, beta 2, beta(3]. In intact pituitary GH4C1 cells, hormones like thyrotropin-releasing hormone and vasoactive intestinal peptide induced a similar conversion from N1 and N2 to P1, P2, and P3. The phosphorylation of both alpha and beta isoforms of stathmin is therefore a physiologically significant response to specific extracellular regulatory agents. In conclusion, stathmin represents a family of at least two distinct protein isoforms, whose respective phosphorylation and expression might play a role in its likely function as an intracellular relay of various converging extracellular signals.
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PMID:Identification of two distinct isoforms of stathmin and characterization of their respective phosphorylated forms. 272 86

We have investigated the possible role of a cAMP-mediated protein-phosphorylation event(s) as the key regulatory mechanism in beta-adrenoreceptor-stimulated activation of mannosylphosphodolichol (Man-P-Dol) synthase (GDP-mannose:dolichyl-phosphate O-beta-D-mannosyltransferase, EC 2.4.1.83) in rat parotid acinar cells. Microsomal membranes isolated from these cells pretreated with 10 microM isoproterenol for 60 min showed approximately 40-80% enhanced Man-P-Dol synthase activity compared to the untreated controls. This change in enzyme activity was not associated with a significant alteration in apparent Km for GDP-mannose, but the Vmax was enhanced 2-fold. When microsomal membranes isolated from control cells were phosphorylated in vitro by a cAMP-dependent protein kinase, an increase in Man-P-Dol synthase activity, similar to that with membranes from isoproterenol-treated cells, was observed (i.e., a moderate change in Km for GDP-mannose but a 2-fold higher Vmax). Furthermore, treatment of in vitro phosphorylated microsomal membranes by alkaline phosphatase led to a substantial reduction in Man-P-Dol synthase activity. Increased Man-P-Dol synthesis (approximately 30-40%) was also observed in bovine brain and hen oviduct microsomal membranes after in vitro protein phosphorylation. In aggregate, these results strongly suggest that agents that increase cAMP in cells may modulate protein N-glycosylation in those cells by activating this key glycosyltransferase of the dolichol cascade by a cAMP-dependent protein kinase-mediated protein phosphorylation/dephosphorylation cycle.
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PMID:cAMP-mediated protein phosphorylation of microsomal membranes increases mannosylphosphodolichol synthase activity. 281 74


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