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

HeLa chromatin core particles contain a protein kinase which transfers phosphate from ATP to both nonhistone proteins and histones. The enzyme preferentially modifies H3 among the histones; about 7% of the H3 molecules in the nucleoprotein are modified at saturation. Activity of this kinase likely contributed to earlier results using crosslinking methodology to study which histones interact with the ends of core particle DNA. When the kinase is largely removed by sedimentation of core particles through sucrose gradients containing 0.45 M NaCl, crosslinking of the 5'-terminal label on DNA is observed only to histone H3. The overall efficiency of the crosslinking reaction is about 15%. The origin of the 5'-terminal 32P previously assigned as crosslinked to H4 is not explained by the current experiments.
...
PMID:Protein kinase in HeLA nucleosomes: a reevaluation of the interactions of histomes with the ends of core particle DNA. 65 16

A mechanism of mitosis-specific enhancement of histone H3 phosphorylation was analyzed in vitro in terms of nucleosome structure. The incorporation of [32P]phosphate into DNA-bound H3 was approximately 5-7 times higher than in DNA-free H3 using the catalytic subunit of cAMP-dependent protein kinase. The two major N-terminal serine sites, including the mitosis-specific site (Ser10) and Ser28, were extensively phosphorylated in the DNA-bound forms. These phosphorylation patterns were identical to those of nucleosomal H3. In contrast, the H3 in DNA-free octamers was very slightly phosphorylated. The major site of H3 phosphorylation in DNA-free H3 was Thr118 in the C-terminus. Results indicate that DNA-binding is essential for the high level of mitosis-specific H3 phosphorylation, and that the nucleosome structure promotes H3 N-terminal phosphorylation in vitro. It also suggests the possibility that H1 prevents H3 phosphorylation during interphase of the cell cycle.
...
PMID:Mitosis-specific histone H3 phosphorylation in vitro in nucleosome structures. 240 Dec 99

To investigate substrates for cyclic AMP-dependent protein kinase in intact islets of Langerhans, batches of islets were incubated with [32P]Pi for 1 h in the presence of 10 mM-glucose; the adenylate cyclase activator forskolin, which in parallel experiments was shown to increase islet cyclic AMP content and insulin release, was then added. Islets were homogenized and subcellular fractions prepared by differential centrifugation. Phosphopeptides were electrophoresed on sodium dodecyl sulphate/polyacrylamide gels and quantified by autoradiography and densitometry. Within 5 min forskolin caused increased labelling of Mr-25 000 and -30 000 cytosolic and Mr-23 000 and -32 000 particulate peptides; a rapid decrease in phosphorylation of Mr-18 000 and -34 000 cytosolic peptides was also observed. In addition, rather slower phosphorylation occurred of the Mr-15 000 peptide previously identified as histone H3 [Christie & Ashcroft (1984) Biochem. J. 218, 87-99]. When similar subcellular fractions were incubated with [gamma-32P]ATP and purified catalytic subunit of cyclic AMP-dependent protein kinase, peptides phosphorylated included cytosolic species of Mr 25 000 and 30 000 and particulate species of Mr 23 000 and 32 000. The distribution of RNA in the subcellular fractions suggested that the Mr-32 000 species could be a ribosomal protein. The 24 000 g pellet was heterogeneous, as judged by marker assays, and was therefore fractionated further by Percoll-density-gradient centrifugation. The peak containing the Mr-23 000 peptide was resolved from marker enzymes for plasma membranes, mitochondria and endoplasmic reticulum and coincided with a peak for insulin: hence the Mr-23 000 peptide is likely to be a secretory-granule component. The study demonstrates that the potentiation of insulin release that occurs when islet cyclic AMP is increased is accompanied by rapid phosphorylation of specific islet substrates for cyclic AMP-dependent protein kinase. The data are consistent with the hypothesis that protein phosphorylation is involved in the regulation of insulin secretion.
...
PMID:Substrates for cyclic AMP-dependent protein kinase in islets of Langerhans. Studies with forskolin and catalytic subunit. 298 5

In order to understand how the phosphorylation of histones affects the chromatin structure, we used electron microscopy, sedimentation velocity, circular dichroism and electric birefringence to monitor the salt-induced filament reversible solenoid transition of phosphorylated and native chromatin. Phosphorylation in vitro of chicken erythrocyte chromatin by cyclic-AMP-dependent protein kinase from porcine heart led to the modification of the histones H3 and H5 only, which were modified at a level of one phosphate and about three phosphate groups per molecule, respectively. In contrast to circular dichroism and sedimentation studies, which tend to suggest that phosphorylation of H3 and H5 does not affect chromatin structure, electron microscopy reveals that phosphorylation causes a relaxation of structure at low ionic strength. Electric birefringence and relaxation time measurements clearly prove that local structural changes are induced in chromatin: we observe a decrease of the steady-state birefringence with the appearance of a negative contribution in the signal and a marked increase of the flexibility of fibres. The component with the negative birefringence presents very short relaxation times, like those exhibited by small DNA fragments or individual nucleosomes. Two possibilities are then suggested. First, the conformational change is consistent with what would be expected from the presence of DNA segments loosely associated with the core histone H3. That the length of such segments could correspond to about one to two base-pairs per nucleosome strongly suggests that phosphorylation induces changes affecting some specific H3-DNA interactions only. This result could corroborate previous observations indicating that the N-terminal region of H3, where the site of phosphorylation is located, plays a decisive role in maintaining the superstructure of chromatin. Second, phosphorylation could introduce hinge points between each nucleosome. In this case, the negative birefringence results from partial orientation of the swinging nucleosomes. A possible mode of action of phosphorylation might be to weaken structural restraints imposed by histone H3, thus facilitating further condensation of chromatin.
...
PMID:Histone phosphorylation in native chromatin induces local structural changes as probed by electric birefringence. 408 98

Phosphorylation of a characteristic subset of nuclear proteins is increased in rat liver cells stimulated with glucagon. Regulated proteins include histones H1 and H3, an HMG 14-like protein and a previously unidentified 23-kDa basic protein. The effect of glucagon is mimicked by forskolin and exogenous cAMP. Insulin and dexamethasone have no effect. In a cell-free system containing purified hepatocyte nuclei, addition of cAMP-dependent protein kinase results in phosphorylation of histone H3, an HMG 14-like protein and a 23-kDa basic protein similar or identical to the protein phosphorylated in vivo.
...
PMID:Phosphorylation of histones and non-histone nuclear proteins in liver cells stimulated by glucagon and cyclic AMP. 609 55

Ca2+ is prominant in the control of cell proliferation and function. However, the biochemical mechanism(s) mediating its effects on nuclear events is unknown. We report here that Ca2+, at physiological concentrations, stimulates the phosphorylation of histone H3 by an endogenous protein kinase in HeLa cell nuclei. Also, pretreatment of cells with Na butyrate, which increases histone acetylation, selectively increases the susceptability of histone H3 to phosphorylation by the protein kinase. Our results reveal a potential link between histone H3 acetylation and phosphorylation, modifications which are thought to have important effects on chromatin structure and function and suggest a possible mechanism whereby stimuli at the cell surface (such as hormones, mitogens and drugs) may influence biochemical events at the nuclear level; changes in the intracellular Ca2+ concentration may influence the phosphorylation of chromosomal proteins, mediated by Ca2+ -dependent kinases in th nucleus.
...
PMID:Calcium-dependent phosphorylation of histone H3 in butyrate-treated HeLa cells. 625 82

Nerve growth factor (NGF), epidermal growth factor (EGF), insulin, cholera toxin (CT) and cAMP all stimulate the phosphorylation of proteins in the PC12 nerve-like cell line. NGF, CT and cAMP enhance phosphorylation of the same set of proteins including tyrosine hydroxylase, ribosomal protein S6, histones H1 and H3, and the nonhistone chromosomal and cytoplasmic high mobility group (HMG) 17 protein, and reduce phosphorylation of H2A. EGF but not insulin enhances the phosphorylation of tyrosine hydroxylase. Insulin but not EGF enhances the phosphorylation of histone H3 and decreases the phosphorylation of H2A. EGFD and insulin each enhance phosphorylations of both ribosomal protein S6 and histone H1, but neither hormone induces phosphorylation of HMG 17. The extent of these effects depends upon the ligand concentration and is half-maximal at physiological concentrations of the hormones (beta-NGF, 2 ng/ml; EGF, 1 ng/ml. insulin, 0.5 microunits/ml). Maximal effects of NGF are seen within 15 min and persist even after 3 days of culture in the presence of NGF. When phosphorylation of ribosomal protein S6 is maximally stimulated by NGF, no further stimulation can be achieved by adding saturating quantities of either cAMP or CT. However, simultaneous addition of saturating quantities of NGF and either EGF or insulin results in an enhancement of phosphorylation that is equal to the sum of that achieved when the two ligands are added separately. These results suggest that the enhanced phosphorylation of S6 achieved by NGF or cAMP occurs through a common mechanism which differs from those which mediate EGF or insulin-enhanced phosphorylation. The data also provide strong evidence that the action of NGF included protein phosphorylation mediated by cAMP-dependent protein kinase. The phosphorylation of each of these proteins in response to NGF may play an important role in NGF action.
...
PMID:Nerve growth factor mediates phosphorylation of specific proteins. 625 87

We have developed a simple in vitro system for studying phosphorylation in isolated HeLa metaphase chromosomes which utilizes the endogenous protein kinase and phosphoprotein phosphatase activities in the chromosomes. Because the isolated chromosomes retain the specificity of phosphorylation seen in vivo, this system offers unique possibilities for studying the properties and regulation of the kinase and phosphatase by adding exogenous substances and observing their effects. It should also be useful for studying the sites of phosphorylation, since proteins can be more easily labeled to high specific activity with 32P in this system than in vivo. The pattern of proteins phosphorylated in isolated metaphase chromosomes appears to be nearly identical with the pattern found in vivo. Among the histones (H) only H1 and H3 are phosphorylated, but several nonhistone proteins, including high mobility group (HMG) 14, are also phosphorylated. Since HMG 14 has been implicated as a structural protein of actively transcribing chromatin, our results suggest that phosphorylation of chromatin proteins may be involved in the shutoff of transcription during mitosis. Tryptic peptide maps and analysis of the phosphorylated amino acids indicate that H1A, H1B, HMG 14, and H3 are phosphorylated at the same sites in vitro in metaphase chromosomes as in mitotic cells in vivo. The major site of phosphorylation of histone H3, both in vivo and in vitro, has been identified as serine 10. HMG 14 is phosphorylated both at serine and threonine residues.
...
PMID:Phosphorylation of histones 1 and 3 and nonhistone high mobility group 14 by an endogenous kinase in HeLa metaphase chromosomes. 628 Dec 54

Earlier, we reported (N. J. Lassam, S. T. Bayley, F. L. Graham, and P. E. Branton, Nature (London) 277:241-243, 1979) detecting protein kinase activity when cytoplasmic extracts of human adenovirus type 5 (Ad5)-infected KB cells immunoprecipitated with 14b antitumor serum directed against the transforming proteins of Ad5, were incubated with [gamma-32P]ATP. Here we show that in the in vitro assay this kinase phosphorylated both the heavy chain of immunoglobulin G and polypeptide than comigrated on sodium dodecyl sulfate gels with the 58,000-dalton Ad5 antigen. It also phosphorylated added histone H3. Evidence is presented that the protein kinase activity found with extracts from Ad5-infected cells is not due to nonspecific trapping of cellular enzymes in immune complexes, but to an enzyme which is distinct from kinases detected at background levels in controls. Serine and threonine were the major phosphorylated amino acids, and essentially no phosphotyrosine was detected. Protein kinase activity detected in Ad12-infected cells immunoprecipitated by an antiserum derived from hamsters bearing Ad12-induced tumors appeared to be immunologically distinct from that immunoprecipitated from Ad5-infected cells by 14b serum.
...
PMID:Protein kinase activity immunoprecipitated from adenovirus infected cells by sera from tumor-bearing hamsters. 721 34

Chromosome condensation at mitosis correlates with the activation of p34cdc2 kinase, the hyperphosphorylation of histone H1 and the phosphorylation of histone H3. Chromosome condensation can also be induced by treating interphase cells with the protein phosphatase 1 and 2A inhibitors okadaic acid and fostriecin. Mouse mammary tumour FT210 cells grow normally at 32 degrees C, but at 39 degrees C they lose p34cdc2 kinase activity and arrest in G2 because of a temperature-sensitive lesion in the cdc2 gene. The treatment of these G2-arrested FT210 cells with fostriecin or okadaic acid resulted in full chromosome condensation in the absence of p34cdc2 kinase activity or histone H1 hyperphosphorylation. However, phosphorylation of histones H2A and H3 was strongly stimulated, partly through inhibition of histone H2A and H3 phosphatases, and cyclins A and B were degraded. The cells were unable to complete mitosis and divide. In the presence of the protein kinase inhibitor starosporine, the addition of fostriecin did not induce histone phosphorylation and chromosome condensation. The results show that chromosome condensation can take place without either the histone H1 hyperphosphorylation or the p34cdc2 kinase activity normally associated with mitosis, although it requires a staurosporine-sensitive protein kinase activity. The results further suggest that protein phosphatases 1 and 2A may be important in regulating chromosome condensation by restricting the level of histone phosphorylation during interphase, thereby preventing premature chromosome condensation.
...
PMID:Chromosome condensation induced by fostriecin does not require p34cdc2 kinase activity and histone H1 hyperphosphorylation, but is associated with enhanced histone H2A and H3 phosphorylation. 788 43


1 2 3 4 5 6 7 8 9 10 Next >>

---