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 nuclear protein P1 (molecular mass 53 kDa), found in all mammalian cell types and tissues so far tested, is an excellent substrate for casein kinase-2. The number of phosphate groups on P1 is 20-30/molecule; the phosphorylation sites are distributed throughout the molecule. The phosphate is present as serine phosphate and possibly threonine phosphate. Proteolytic digestion with Staphylococcus aureus V8 protease of 32P-labelled P1 both in vivo and in vitro revealed that casein kinase-2 may be one of the kinases responsible for the phosphorylation in vivo.
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PMID:Phosphorylation of the high-mobility-group-like protein P1 by casein kinase-2. 280 36

Human pluripotential embryonic teratocarcinoma cells differentially expressed gene activity controlled by the human immunodeficiency virus type 1 (HIV-1) and human T-cell leukemia virus type I (HTLV-I) long terminal repeats (LTRs) when differentiation was induced by the morphogen all-trans retinoic acid. The alterations occurred after commitment and before the appearance of the multiple cell types characteristic of these pluripotential cells. After commitment, gene activity controlled by the HIV-1 LTR markedly increased, whereas that controlled by the HTLV-I LTR decreased. Steady-state mRNA levels and nuclear run-on transcription indicated that the increased HIV-1-directed activity during differentiation occurred posttranscriptionally, whereas the decreased HTLV-I activity was at the transcriptional level. Phorbol esters did not cause commitment but strongly enhanced expression by both viral LTRs at the transcriptional level. A specific inhibitor of protein kinase C, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine, indicated that the enhanced activity involved the activation of protein kinase(s) C; altered cyclic nucleotide metabolism was apparently not involved. Differentiating cells gradually lost the ability to respond to phorbol ester stimulation. Experiments with a deletion mutant of the HIV-1 LTR suggested that this was due to imposition of negative regulation during differentiation that was not reversed by phorbol ester induction. Cycloheximide, with or without phorbol ester, slightly stimulated HIV-1-directed activity at the transcriptional level and massively increased the amounts of steady-state mRNA by posttranscriptional superinduction. It appeared, however, that new nuclear protein synthesis was required for maximal transcriptional stimulation by phorbol esters. Thus, changing cellular regulatory mechanisms influenced human retrovirus expression during human embryonic cell differentiation.
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PMID:Regulation of expression driven by human immunodeficiency virus type 1 and human T-cell leukemia virus type I long terminal repeats in pluripotential human embryonic cells. 283 1

A cAMP binding protein was detected in HL-60 cells using photoaffinity labeling with 8-azido [32P]cAMP. The binding protein was found in a 0.35 M NaCl nuclear protein extract from untreated HL-60 cells and from the HL-60 cells induced to mature with retinoic acid. While the quantity of the cAMP binding protein did not change following the induced differentiation, a second form of the subunit, altered in charge, was present at 3 and 5 days after retinoic acid treatment. The findings indicate that the regulatory subunit of the type II cAMP-dependent protein kinase could be involved in nuclear functions associated with human myeloid cell differentiation.
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PMID:A nuclear cAMP binding protein in retinoic acid-treated HL-60 cells. 284 Apr 43

Transcription of proto-oncogene fos is induced by elevated levels of intracellular cAMP. We report that human c-fos promoter recombinants transfected into rat pheochromocytoma cells (PC12) and human choriocarcinoma cells (JEG-3) are induced by stimulation of adenylate cyclase and that this induction is diminished considerably in the mutant PC12 cell line A126-1B2, which is deficient in cAMP-dependent protein kinase II. An element centered at position -60 of the c-fos promoter, which encompasses a consensus cAMP response element (CRE), is sufficient to confer cAMP responsiveness to a herpes thymidine kinase/CAT fusion gene. The specific binding of a nuclear protein to the c-fos CRE can be competed by the somatostatin and alpha-chorionic gonadotropin (alpha-CG) promoter regions that contain CREs. Gel mobility shift assays with double-stranded oligonucleotides containing either the wild-type or mutated c-fos CRE sequence have demonstrated that binding occurs only to the wild-type CRE. The nuclear factor binding to the c-fos CRE is likely to be transcription factor CREB (CRE nuclear binding protein), because an affinity-purified 43-kD CREB isolated from PC12 cells binds efficiently in a DNA footprinting assay. Thus, regulation of the c-fos gene transcription appears to involve a mechanism common to many genes that respond to cAMP as a second message leading to cell growth and differentiation.
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PMID:Induction of proto-oncogene fos transcription through the adenylate cyclase pathway: characterization of a cAMP-responsive element. 285 Sep 67

The expression of 20 known cellular proto-oncogenes in human well-differentiated hepatoma cell line Hep3B and poorly-differentiated hepatoma cell line HA22T/VGH was studied by Northern blot hybridization. Among the cellular proto-oncogenes examined, both cell lines express protein kinase genes including fps, mos and raf; PDGF B chain sis gene; GTP/GDP binding protein gene Ha-ras and nuclear protein genes including fos and myc. The expression of yes, abl, ros, src, erb-B, erb-A, fms, Ki-ras, myb, rel and bas genes was not detected in both cell lines.
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PMID:Expression of oncogenes in human hepatoma cell lines. 285 43

Many hormones act on neuroendocrine cells by activating second messenger pathways. Two of these, the phosphoinositol and cAMP-dependent pathways, cause changes in cellular activity through specific protein kinases. By phosphorylating cytoplasmic and nuclear proteins, these kinases apparently coordinate cellular processes, including the biosynthesis and release of neuropeptides. Somatostatin biosynthesis and release, for example, are both positively regulated by the second messenger cAMP in hypothalamic cells, and cAMP also induces somatostatin gene transcription 8-10-fold in transfected PC12 pheochromocytoma cells. Transcriptional induction requires a 30-nucleotide cAMP response element (CRE) which is conserved in other cAMP-responsive genes. This element also confers cAMP responsiveness when placed upstream of the heterologous simian virus 40 (SV40) promoter. The somatostatin gene does not, however, respond to cAMP in mutant PC12 cells which lack cAMP-dependent protein kinase type II activity. Activation of somatostatin gene transcription may consequently require the phosphorylation of a nuclear protein which binds to the CRE. Using a DNase I protection assay, we have characterized a nuclear protein in PC12 cells which binds selectively to the CRE in the somatostatin gene. We have purified this protein which is of relative molecular mass 43,000 (Mr 43K) by sequence-specific DNA affinity chromatography. This 43K CRE binding protein (CREB) is phosphorylated in vitro when it is incubated with the catalytic subunit of cAMP-dependent protein kinase. Stimulating PC12 cells with forskolin, an activator of adenyl cyclase, causes a 3-4-fold increase in the phosphorylation of this protein. We conclude that the cAMP-dependent pathway may regulate gene transcription in response to hormonal stimulation by phosphorylating this CREB protein.
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PMID:Binding of a nuclear protein to the cyclic-AMP response element of the somatostatin gene. 288 56

Thiophosphorylation and phosphorylation of 5% perchloric acid extractable proteins from calf thymus chromatin were studied using a cyclic GMP-dependent protein kinase from bovine lung and a nuclear protein kinase II from rat liver. The phosphorylation reaction catalyzed by nuclear protein kinase II utilized [gamma -35S]ATP as a phosphate donor almost as efficiently as [gamma -32P]ATP, but the cGMP-dependent protein kinase mediated phosphorylation by [35S]ATP was about 20 times less effective than that by [32P]ATP. In addition, using [35S]ATP instead of [32P]ATP changed markedly the cGMP-dependent phosphorylation pattern of the PCA-extractable proteins as examined by gel electrophoresis. Thus, depending on the type of protein kinase, the results from thiophosphorylation and phosphorylation reactions may vary considerably.
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PMID:Thiophosphorylation and phosphorylation of chromatin proteins from calf thymus in vitro. 298 63

Hormone-dependent phosphorylation and dephosphorylation of nuclear proteins may play an important part in regulating nuclear function and specific gene expression. Some progress has been made in identifying specific nuclear proteins whose phosphorylation is affected by specific hormones; however, relatively little is known about the regulatory mechanisms involved, or about the molecular consequences of increased or decreased phosphorylation. It is suspected--but not yet proved--that cAMP-dependent effects on transcription are mediated at least partly by increases in nuclear cAMP-dependent protein kinase (A-kinase) activity, and consequent increases in the phosphorylation of specific chromatin proteins. In several instances, increased phosphorylation has been found to precede or correlate with cAMP-mediated induction of specific gene products. Several chromatin proteins are susceptible to cAMP-dependent phosphorylation in vivo, including histones H1 and H3, the high mobility group protein HMG 14 (which is preferentially associated with actively transcribed chromatin), and at least three other basic nonhistone proteins. The A-kinase phosphorylation sites of the majority of H1, H3 and HMG 14 molecules in chromatin appear to be inaccessible to A-kinase in vivo; nothing is known about the factors determining their accessibility, which may be tightly regulated and may vary significantly from cell to cell and tissue to tissue. Many hormone-induced changes in nuclear protein phosphorylation may be cAMP-independent. cAMP-independent mechanisms could involve a variety of nuclear enzymes including, for example, cGMP-dependent, Ca2+/calmodulin-dependent, Ca2+/phospholipid-dependent and polyamine-dependent protein kinases. So far, however, there is little solid evidence in support of a role for any specific cAMP-independent protein kinase in mediating hormonally induced increases in the phosphorylation of specific, identified nuclear proteins.
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PMID:Hormonal control of the phosphorylation of histones, HMG proteins and other nuclear proteins. 298 75

In experiments designed to study the mechanism by which peptide hormones binding to their plasma membrane receptors stimulate the expression of specific genes, the transcription of two neuroendocrine genes, prolactin and growth hormone, was analyzed in a rat pituitary cell line. The results showed that cyclic adenosine monophosphate (cyclic AMP) stimulates the transcription of discrete subsets of eukaryotic genes by at least two independent molecular mechanisms. Cyclic AMP stimulated growth hormone gene transcription and phosphorylation of a 19,000-dalton nuclear protein; this appears to reflect direct nuclear actions of the cyclic AMP-dependent protein kinase. In contrast, the stimulation by cyclic AMP of prolactin gene transcription appears to reflect activation of a discrete calcium-dependent event.
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PMID:Cyclic AMP regulation of eukaryotic gene transcription by two discrete molecular mechanisms. 299 47

A substantial increase in cyclic AMP-dependent protein kinase activity occurred in nuclei of PY815 mastocytoma cells during G1 phase growth arrest by DB cyclic AMP and the increased nuclear protein kinase was accompanied by changes in nuclear protein phosphorylation. However, there was no obligatory association between the rise in nuclear cyclic AMP-dependent protein kinase in G1 phase and growth arrest because nuclear cyclic AMP-dependent protein kinase also increased during G1 phase in cycling PY815 cells synchronized with amethopterin. These observations suggest that maintenance of high cyclic AMP levels during G1 phase may cause growth arrest by activating a cyclic AMP-dependent protein kinase that normally increases in PY815 cell nuclei during G1 phase.
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PMID:Cyclic AMP, nuclear protein kinase and the PY815 cell cycle. 299 42


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