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)

Cyclin A-kinase, an enzyme required for coordinating S phase progression, forms stable in vivo complexes with E2F-1, a growth-promoting transcription factor, which binds to the retinoblastoma gene product and is involved in the timely activation of genes whose products contribute to G1 exit and S phase traversal. Complex formation results in a negative biochemical effect of cyclin A-kinase: the shut-off of E2F-1-dependent DNA binding function in S/G2. Thus, specific and timely cell cycle-dependent interactions of E2F-1 with proteins that inhibit its function (i.e., RB during G1 and cyclin A-kinase during S/G2) may contribute to the periodicity of expression of certain E2F-1-responsive genes at the G1/S transition.
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PMID:Negative regulation of the growth-promoting transcription factor E2F-1 by a stably bound cyclin A-dependent protein kinase. 803 8

Butyrolactone I is a selective inhibitor of the cyclin-dependent kinase (cdk) family. It inhibits both cdk2 and cdc2 kinase, but scarcely affects C-kinase, A-kinase, casein kinases, MAP kinase or EGF receptor-tyrosine kinase (Kitagawa et al., 1993, Oncogene, 8, 2425-2432). We studied the effects of butyrolactone I on the cell cycle as well as on phosphorylation of retinoblastoma protein (pRB). Butyrolactone I inhibited phosphorylation of pRB catalyzed by cyclin A-cdk2 produced by baculovirus in vitro. Furthermore, it inhibited phosphorylation of pRB and cell cycle progression from G1 to S phase in WI38 cell cultures. WI38 cells arrested at the G0 phase by serum starvation progressed in the cell cycle after serum stimulation. pRB was phosphorylated after 10 h serum stimulation. Incorporation of [3H]thymidine into the cells began to increase after 16 h serum stimulation. These processes were inhibited by butyrolactone I. Flow cytometric analysis showed that exposure to butyrolactone I inhibited progression of the cell cycle from G1 to S phase. These data suggested that initiation of DNA synthesis was inhibited by butyrolactone I and that the cell cycle was arrested in the G1 phase. Butyrolactone I also inhibited H1 histone phosphorylation in human WI38 cells and their G2/M progression. tsFT210 cells, a temperature-sensitive cdc2 mutant cell line, were synchronized at G2/M at a nonpermissive temperature, butyrolactone I inhibited the cell cycle progression of these cells at G2/M at the permissive temperature. Thus butyrolactone I, a cyclin-dependent kinase family inhibitor, which prevented the phosphorylations of the cell cycle-regulating proteins pRB and H1 histone, inhibited the cell cycle at G1/S and G2/M, respectively. These results suggest that the phosphorylations of pRB and H1 histone may play crucial roles in G1/S and G2/M progression, respectively, although it is possible that phosphorylations of other proteins by cdks are involved in G1/S and G2/M progression.
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PMID:A cyclin-dependent kinase inhibitor, butyrolactone I, inhibits phosphorylation of RB protein and cell cycle progression. 805 18

The human cytomegalovirus major immediate-early (IE) proteins play an indispensable role in regulating viral gene expression. One of these gene products, the IE2 86-kDa protein (IE2 86), is a potent activator of both homologous and heterologous promoters and can form a complex with a component of the basal transcription apparatus, the TATA box-binding protein (TBP). In this report, we show that when IE2 86 is expressed as a glutathione S-transferase (GST)-IE2 86 fusion protein, there are three independent regions that can interact with TBP and with another important cellular regulatory protein, the retinoblastoma gene product (RB). One of these three regions, as well as a domain at the carboxy terminus, contain consensus sites for casein kinase phosphorylation and negatively regulate binding of in vitro-translated IE2 86 to GST-TBP or GST-RB. The dimerization domain of IE2 86 must be present for the interaction of the in vitro-translated protein with GST-TBP and GST-RB. Analysis of IE2 86 mutants in vivo demonstrates that one of the strong binding regions is required for the protein to function as a transactivator. Our results also indicate that domains other than those that interact with TBP and RB are required for the activation function of this protein.
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PMID:Transactivation by the human cytomegalovirus IE2 86-kilodalton protein requires a domain that binds to both the TATA box-binding protein and the retinoblastoma protein. 808 62

A family of vertebrate cdc2-related kinases has been identified, and these kinases are candidates for roles in cell cycle regulation. Here, we show that the human PLSTIRE gene product is a novel cyclin-dependent kinase, cdk6. The cdk6 kinase is associated with cyclins D1, D2, and D3 in lysates of human cells and is activated by coexpression with D-type cyclins in Sf9 insect cells. Furthermore, we demonstrate that endogenous cdk6 from human cell extracts is an active kinase which can phosphorylate pRB, the product of the retinoblastoma tumor suppressor gene. The activation of cdk6 kinase occurs during mid-G1 in phytohemagglutinin-stimulated T cells, well prior to the activation of cdk2 kinase. This timing suggests that cdk6, and by analogy its homolog cdk4, links growth factor stimulation with the onset of cell cycle progression.
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PMID:Identification of G1 kinase activity for cdk6, a novel cyclin D partner. 811 39

Members of the cell division cycle 2 (CDC2) family of kinases play a pivotal role in the regulation of the eukaryotic cell cycle. In this communication, we report the isolation of a cDNA that encodes a CDC2-related human protein kinase temporarily designated PITALRE for the characteristic Pro-Ile-Thr-Ala-Leu-Arg-Glu motif. Its deduced amino acid sequence is 47% identical to that of the human cholinesterase-related cell division controller (CHED) kinase, which is required during hematopoiesis, and 42% identical to the Saccharomyces cerevisiae SGV1 gene product, a putative kinase involved in the response to pheromone via its guanine nucleotide-binding protein alpha subunit. PITALRE expression is ubiquitous, but its expression levels are different in various human tissues. PITALRE is an approximately 43-kDa protein that associates with three cellular polypeptides of 80, 95, and 155 kDa. PITALRE is localized primarily to the nucleus. In addition, we have identified a retinoblastoma protein kinase activity associated with PITALRE immunocomplexes that cannot phosphorylate histone H1, suggesting that the target phosphorylation site of PITALRE differs from that of CDC2 kinase. Interestingly, the retinoblastoma kinase activity associated with PITALRE does not oscillate during the cell cycle.
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PMID:PITALRE, a nuclear CDC2-related protein kinase that phosphorylates the retinoblastoma protein in vitro. 817 Sep 97

The retinoblastoma gene product (Rb) can interact efficiently with two of three D-type G1 cyclins (D2 and D3) in vitro. Binding depended upon the minimal regions of Rb necessary for its growth-suppressive activity, as well as upon the D-type cyclin sequence motif shared with Rb-binding DNA tumor virus oncoproteins. Coexpression of the three D-type cyclins with the cyclin-dependent kinase (cdk4) in insect cells generated Rb kinase activity. By contrast, cyclins D2 and D3, but not D1, activated another such kinase, cdk2. Introduction of cyclin D2 and Rb into the Rb-deficient cell line SAOS-2 led to overt Rb hyperphosphorylation, whereas Rb, expressed alone or together with cyclin D1, remained unphosphorylated. Cyclin D2-dependent phosphorylation inhibited its binding to the transcription factor E2F and reversed the Rb G1 exit block in the cell cycle. Thus, all D-type cyclins do not function equivalently, and one of them plays a major role in reversing the cycle-blocking function of a known tumor suppressor.
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PMID:Functional interactions of the retinoblastoma protein with mammalian D-type cyclins. 834 2

We screened cdc2 kinase inhibitors from cultured mediums of micro organisms using purified mouse cyclin B-cdc2 kinase and a specific substrate peptide for cdc2 kinase. A selective inhibitor of cdc2 kinase was isolated from the cultured medium of Aspergillus species F-25799, and identified as butyrolactone I. Butyrolactone I inhibited cdc2 and cdk2 kinases but it had little effect on mitogen-activated protein kinase, protein kinase C, cyclic-AMP dependent kinase, casein kinase II, casein kinase I or epidermal growth factor-receptor tyrosine kinase. Its inhibitory effect was found to be due to competition with ATP. Butyrolactone I selectively inhibited the H1 histone phosphorylation in nuclear extracts. It also inhibited the phosphorylation of the product of retinoblastoma susceptibility gene in nuclear extracts and intact cells. Thus butyrolactone I should be very useful for elucidating the function of cdc2 and cdk2 kinases in cell cycle regulation.
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PMID:Butyrolactone I, a selective inhibitor of cdk2 and cdc2 kinase. 839 80

Transforming growth factor beta 1 (TGF beta 1) causes G1 growth arrest and the accumulation of unphosphorylated retinoblastoma protein (Rb) in responsive cells. Cdk4 (cyclin-dependent kinase), a major catalytic subunit of the mammalian D-type G1 cyclins, can phosphorylate Rb in vitro, and at least one D-type cyclin, D2, directs the phosphorylation of Rb in vivo. Here we show that TGF beta 1 induces suppression of cdk4 synthesis in G1 in mink lung epithelial cells. Constitutive cdk4 synthesis in these cells led to TGF beta 1 resistance. It also resulted in growth in low serum medium when these cells were released from contact inhibition. Cdk2 activity was also suppressed by TGF beta 1 action, but its constitutive expression failed to override a TGF beta 1-induced G1 block. Hence, the TGF beta 1 block is primarily mediated by cdk4 modulation. Further evidence suggests that TGF beta 1-induced down-modulation of cdk4 leads to inhibition of cdk2 activation and that both events might contribute to TGF beta 1 growth suppression.
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PMID:TGF beta inhibition of Cdk4 synthesis is linked to cell cycle arrest. 840 78

Interleukin 6 (IL-6) induces in M1 myeloblastic cells growth arrest and terminal differentiation toward monocytes. It is reported here that IL-6 reduced by 5- to 20-fold the tyrosine phosphorylation of cellular proteins in these cells. The same-fold reduction was also observed in M1 cells that were transfected with the BCR-ABL deregulated protein kinase. In these stable clones, the levels of tyrosine phosphorylation of cellular proteins were 30- to 100-fold higher than in the parental cells. IL-6 did not reduce the expression levels or the inherent tyrosine kinase activity of BCR-ABL p210. By measuring the protein-tyrosine-phosphatase (PTPase; protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) activity in crude cell lysates, we found that protein dephosphorylation resulted, at least partially, from induction of PTPase activity by IL-6. The induction of PTPase in the BCR-ABL-transfected clones was not sufficient to confer the minimal protein phosphorylation levels characteristic of IL-6-treated cells. Yet, the transfected M1 clones showed normal growth and differentiation responses to IL-6. None of the gene responses to IL-6 including suppression in the levels of c-myc, c-myb, and cyclin A mRNA; junB and c-jun mRNA induction; and dephosphorylation of retinoblastoma protein were rescued by the BCR-ABL oncogene. The functional relevance of PTPase induction by IL-6 is discussed.
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PMID:Induction of protein-tyrosine-phosphatase activity by interleukin 6 in M1 myeloblastic cells and analysis of possible counteractions by the BCR-ABL oncogene. 842 78

The ability of the high-risk and low-risk human papillomavirus E7 oncoproteins to disrupt complexes of the retinoblastoma tumor suppressor protein pRB and the cellular transcription factor E2F was studied. The ability of E7 to disrupt this transcription factor complex correlated with the different pRB binding efficiencies of the high-risk and low-risk human papillomavirus-encoded E7 proteins. The pRB binding site was the sole determinant for these observed differences. The phosphorylation status of the casein kinase II site that is immediately adjacent to the pRB binding site in E7 had no marked effect on this biochemical property of E7. Peptides consisting of the pRB binding site of E7, however, were not able to disrupt the pRB/E2F complex. These data suggest that additional carboxy-terminal sequences in E7 are also required for the efficient disruption of the pRB/E2F complex and that E7 and E2F may interact with nonidentical sites of pRB.
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PMID:The human papillomavirus E7 oncoprotein and the cellular transcription factor E2F bind to separate sites on the retinoblastoma tumor suppressor protein. 844 36


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