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:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two soybean cDNA clones, SPK-3 and SPK-4, encoding putative protein kinases were isolated and characterized. Both cDNAs encoded approximately 40-kDa serine/threonine kinases with unusual stretches of acidic amino acids in their carboxy-terminal regions, which are highly homologous to PKABA1 from wheat and ASKs from Arabidopsis. These kinases are encoded by one- or two-copy genes in the soybean genome. Notably, SPK-3 and -4 showed different patterns of expression in various soybean tissues. SPK-3 is highly expressed in dividing and elongating tissues of young seedlings but relatively weakly in tissues of mature plants. In contrast, SPK-4 showed relatively high and constitutive expression in all the tissues examined except for leaf tissues of mature plants. Although various stressors, such as dehydration and high salinity, increased the expression of both genes, the induction kinetics were different. The two genes also differed in their response to abscisic acid (ABA). SPK-3 was induced but SPK-4 was not affected by exogenously supplied abscisic acid. In accordance with these expression data analysis of the activity of a chimeric SPK-3 promoter::beta-glucuronidase (GUS) reporter gene by transient expression in tobacco leaves confirmed the inducibility of SPK-3 by salt and ABA. Polyclonal antibodies raised against a recombinant SPK-4 protein produced in Escherichia coli specifically recognized both recombinant SPK-3 and -4 proteins. Kinase assays using affinity-purified SPK-4/ antibody complexes with crude soybean extracts as substrate identified specific phosphorylation of two 41 and 170 kDa soybean proteins that were phosphorylated on serine residues. Taken together, our results suggest that SPK-3, and/or SPK-4 are functional serine protein kinase(s). Furthermore, SPK-3 and -4 may play different roles in the transduction of various environmental stresses.
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PMID:Differential expression of two functional serine/threonine protein kinases from soybean that have an unusual acidic domain at the carboxy terminus. 926 31

The maize abscisic acid-responsive Rab17 protein localizes to the nucleus and cytoplasm in maize cells. In-frame fusion of Rab17 to the reporter protein beta-glucuronidase (GUS) directed GUS to the nucleus and cytoplasm in transgenic Arabidopsis thaliana and in transiently transformed onion cells. Analysis of chimeric constructs identified one region between amino acid positions 66-96, which was necessary for targeting GUS to the nucleus. This region contains a serine cluster followed by a putative consensus site for protein kinase CK2 phosphorylation, and a stretch of basic amino acids resembling the simian virus 40 large T antigen-type nuclear localization signal (NLS). Mutation of two basic amino acids in the putative NLS had a weak effect on nuclear targeting in the onion cell system and did not modify the percentage of nuclear fusion protein in the Arabidopsis cells. The mutation of three amino acids in the consensus site for CK2 recognition resulted in the absence of in vitro phosphorylated forms of Rab17 and in a strong decrease of GUS enzymatic activity in isolated nuclei of transgenic Arabidopsis. These results suggest that phosphorylation of Rab17 by protein kinase CK2 is the relevant step for its nuclear location, either by facilitating binding to specific proteins or as a direct part of the nuclear targeting apparatus.
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PMID:Phosphorylation mediates the nuclear targeting of the maize Rab17 protein. 968 Oct 11

The phytohormone abscisic acid (ABA) induces genes-encoding proteins involved in desiccation tolerance and dormancy in seeds, but ABA also suppresses gibberellin (GA)-responsive genes encoding hydrolytic enzymes essential for postgermination growth. A unique serine/threonine protein kinase, PKABA1 mRNA, up-regulated by ABA in seeds, has been identified. In this report, the effect of PKABA1 on the signal transduction pathway mediating ABA induction and suppression of genes has been determined in aleurone layers of barley seeds. Two groups of gene constructs were introduced to barley aleurone layers by using particle bombardment: the reporter constructs containing the coding sequence of beta-glucuronidase gene linked to hormone-responsive promoters and the effector constructs containing the coding region of protein kinases linked to a constitutive promoter. Constitutive expression of PKABA1 drastically suppressed expression of low- and high-pI alpha-amylase and protease genes induced by GA. However, the presence of PKABA1 had only a small effect on the ABA induction of a gene encoding a late embryogenesis abundant protein, HVA1. Our results indicate that PKABA1 acts as a key intermediate in the signal transduction pathway leading to the suppression of GA-inducible gene expression in cereal aleurone layers.
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PMID:An abscisic acid-induced protein kinase, PKABA1, mediates abscisic acid-suppressed gene expression in barley aleurone layers. 999 99

The type V transforming growth factor beta (TGF-beta) receptor (TbetaR-V) is a ligand-stimulated acidotropic Ser-specific protein kinase that recognizes a motif of SXE/S(P)/D. This motif is present in the cytoplasmic domain of the mannose 6-phosphate/insulin-like growth factor-II (Man-6-P/IGF-II) receptor. We have explored the possibility that the Man-6-P/IGF-II receptor is a substrate of TbetaR-V. Purified bovine Man-6-P/IGF-II receptor was phosphorylated by purified bovine TbetaR-V in the presence of [gamma-32P]ATP and MnCl2 with an apparent Km of 130 nM. TGF-beta stimulated the phosphorylation of the Man-6-P/IGF-II receptor at 0 degrees C in mouse L cells overexpressing the Man-6-P/IGF-II receptor and in wild-type mink lung epithelial (Mv1Lu cells) metabolically labeled with [32P]orthophosphate. The in vitro and in vivo phosphorylation of the Man-6-P/IGF-II receptor occurred at the putative phosphorylation sites as revealed by phosphopeptide mapping and amino acid sequence analysis. TGF-beta stimulated Man-6-P/IGF-II receptor-mediated uptake (approximately 2-fold after 12 h treatment) of exogenous beta-glucuronidase in Mv1Lu cells and type II TGF-beta receptor (TbetaR-II)-defective mutant cells (DR26 cells) but not in type I TGF-beta receptor (TbetaR-I)-defective mutant cells (R-1B cells) and human colorectal carcinoma cells (RII-37 cells) expressing TbetaR-I and TbetaR-II but lacking TbetaR-V. These results suggest the Man-6-P/IGF-II receptor serves as an in vitro and in vivo substrate of TbetaR-V and that both TbetaR-V and TbetaR-I may play a role in mediating the TGF-beta-stimulated uptake of exogenous beta-glucuronidase.
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PMID:The mannose 6-phosphate/insulin-like growth factor-II receptor is a substrate of type V transforming growth factor-beta receptor. 1039 50

We have isolated and characterized the genomic clone of maize casein kinase 2 (CK2) alpha subunit using the previously described alphaCK2-1 cDNA clone as a probe. The genomic clone is 7.5 kb long and contains 10 exons, separated by 9 introns of different size, two larger than 1.5 kb and the others around 100-150 bp. The sequence of the exons is 100% homologous to the sequence of the alphaCK2-1 cDNA. Southern hybridization of total genomic DNA from maize embryos with aCK2 cDNA indicated that the alphaCK2-1 gene is part of a multigenic family. We also isolated a new embryo cDNA clone coding for an alphaCK2-2 subunit. We studied the regulation of the enzyme in embryos at the mRNA level, at the protein level and by activity testing. By using immunocytochemistry the CK2 protein was localized in several types of cells of mature embryos. Particularly strong signals were visible in the cytoplasm of epidermis and meristematic cells. Decoration of nuclei of root cortex and scutellum cells was also observed suggesting that CK2 can shift from the cytoplasm into nuclei in specific cell types. We examined whether CK2 contained specific protein domains which actively target the protein to the nucleus by using in-frame fusions of the maize CK2alpha subunit to the reporter gene encoding beta-glucuronidase (GUS) which were assayed in transiently transformed onion epidermal cells. Analysis of chimeric constructs identified one region containing a nuclear localization signal (NLS) that is highly conserved in other alphaCK2 proteins.
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PMID:Characterization, subcellular localization and nuclear targeting of casein kinase 2 from Zea mays. 1041

Chimeric Ca(2+)/calmodulin-dependent protein kinase (CCaMK) was cloned from developing anthers of lily (Lilium longiflorum Thumb. cv. Nellie White) and tobacco (Nicotiana tabacum L. cv. Xanthi). Previous biochemical characterization and structure/function studies had revealed that CCaMK has dual modes of regulation by Ca(2+) and Ca(2+)/calmodulin. The unique structural features of CCaMK include a catalytic domain, a calmodulin-binding domain, and a neural visinin-like Ca(2+)-binding domain. The existence of these three features in a single polypeptide distinguishes it from other kinases. Western analysis revealed that CCaMK is expressed in a stage-specific manner in developing anthers. Expression of CCaMK was first detected in pollen mother cells and continued to increase, reaching a peak around the tetrad stage of meiosis. Following microsporogenesis, CCaMK expression rapidly decreased and at later stages of microspore development, no expression was detected. A tobacco genomic clone of CCaMK was isolated and transgenic tobacco plants were produced carrying the CCaMK promoter fused to the beta-glucuronidase reporter gene. Both CCaMK mRNA and protein were detected in the pollen sac and their localizations were restricted to the pollen mother cells and tapetal cells. Consistent results showing a stage-specific expression pattern were obtained by beta-glucuronidase analysis, in-situ hybridization and immunolocalization. The stage- and tissue-specific appearance of CCaMK in anthers suggests that it could play a role in sensing transient changes in free Ca(2+) concentration in target cells, thereby controlling developmental events in the anther.
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PMID:Developmental regulation of the gene for chimeric calcium/calmodulin-dependent protein kinase in anthers. 1043 17

Abcission, the natural shedding of leaves, flowers and fruits, is a fundamental component of plant development. Abscission is a highly regulated process that occurs at distinct zones of cells that undergo enlargement and subsequent separation. Although some components of abscission, including accumulation of the hormone ethylene and cell wall-degrading enzymes, have been described, the regulatory pathways remain largely unknown. In this paper we describe a critical component required for floral organ abscission in Arabidopsis thaliana, the receptor-like protein kinase HAESA. Histochemical analysis of transgenic plants harboring a HAESA promoter:: beta-glucuronidase reporter gene and in situ RNA hybridization experiments show HAESA expression in the abscission zones where the sepals, petals, and stamens attach to the receptacle, at the base of pedicels, and at the base of petioles where leaves attach to the stem. Immunodetection, immunoprecipitation, and protein kinase activity assays reveal HAESA is a plasma membrane serine/threonine protein kinase. The reduction of function of HAESA in transgenic plants harboring an antisense construct results in delayed abscission of floral organs, and the severity of the phenotype is directly correlated with the level of HAESA protein. These results demonstrate that HAESA functions in developmentally regulated floral organ abscission.
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PMID:HAESA, an Arabidopsis leucine-rich repeat receptor kinase, controls floral organ abscission. 1064 Feb 80

Cell division and differentiation continue throughout the plant life cycle without significant loss of control. However, little is known about the mechanisms that allow the continuous development of meristems. Cell division is controlled by a family of cyclin-dependent kinases (CDKs). CDK-activating kinases (CAKs) are known to phosphorylate and activate almost all CDKs and thus may have a crucial role in controlling CDK activities in each cell of the meristems. Here, we show that overexpression of sense or antisense gene for Cak1At in Arabidopsis by using the glucocorticoid-mediated transcriptional induction system resulted in a reduction of CDK activities. After 14-24 h of glucocorticoid treatment, starch granules appeared in columellar initials in the root meristem, and cortical initials were periclinally divided into cortical and endodermal cells. Accumulation of the cyclin beta-glucuronidase fusion protein ceased after 72 h of glucocorticoid treatment. Our results indicate that a change of Cak1At activity leads to differentiation of initial cells, followed by cessation of cell division. Therefore, we propose that differentiation of initial cells is controlled by Cak1At but is maintained independent of cell division.
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PMID:A cyclin-dependent kinase-activating kinase regulates differentiation of root initial cells in Arabidopsis. 1106 5

Extracellular ATP suppressed the growth of HL-60 leukemia cells and induced their differentiation as revealed by N-formyl-methionyl-leucyl-phenylalanine-induced beta-glucuronidase release. ATP degraded to ADP, AMP, and adenosine, and the effect of ATP on cell growth was mimicked by these metabolites added to the cultures. The stable analog alpha,beta-methylene ATP, however, had only a weak inhibitory effect on cell growth. Adenine nucleotide-induced growth suppression was reversed by uridine, suggesting the involvement of intracellular pyrimidine starvation secondary to adenosine accumulation. Consistent with this, ATP induced intracellular starvation of pyrimidine nucleotides, and this effect was also prevented by pretreatment of cells with uridine. The order of effectiveness of ATP-induced differentiation of HL-60 cells, unlike that for growth suppression, was ATP > ADP > AMP, and adenosine had no effect. Furthermore, uridine had no effect and the stable analog, alpha,beta-methylene ATP also induced HL-60 cell differentiation, suggesting that differentiation was due to ATP per se. We tested the hypothesis that ATP-induced differentiation arises from activation of adenylyl cyclase by the novel P2Y(11) receptor using the cell-permeable inhibitor of protein kinase A, Rp-CPT-cAMPS (8-(4-chlorophenylthio)adenosine-3',5'-cyclic monophosphorothioate, Rp isomer). Rp-CPT-cAMPS (1-100 microM) prevented ATP-induced differentiation of HL-60 cells as assessed by fMLP-induced beta-glucuronidase release. However, Rp-CPT-cAMPS did not prevent ATP-induced growth suppression. Taken together, the data indicate that extracellular ATP suppresses HL-60 growth and induces their differentiation by distinct mechanisms. Growth suppression arises from adenosine generation and consequent pyrimidine starvation. Differentiation arises, at least in part, from a distinct mechanism involving the activation of cell surface P2 receptors coupled to cAMP generation and activation of protein kinase A.
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PMID:Extracellular ATP-dependent suppression of proliferation and induction of differentiation of human HL-60 leukemia cells by distinct mechanisms. 1107 40

Hyperosmotic stress severely affects plant growth and development. To examine the effect of salt stress on cell cycle activity in Arabidopsis thaliana (L.) Heynh., the transcriptional regulation of a cyclin-dependent kinase, CDC2aAt, and two mitotic cyclins, Arath;CycB1;1 and Arath;CycA2;1, was studied by using the beta-glucuronidase (gus) reporter gene. Moreover, the mRNA abundance of these cell cycle genes as well as CDC2bAt were monitored during salt stress. Upon NaCl treatment, the promoter activities and transcript levels of all cell cycle genes diminished initially in the shoot apex and were subsequently induced during salt-stress adaptation. Additionally, the promoter activities of CDC2aAt and CycA2;1 decreased in the vascular cylinder of the root in correlation with reduced lateral root formation. In the root tips, a regression of CDC2aAt, CycA2;1, and CycB1;1:gus expression was observed, concomitant with a shrinkage of the root meristem and inhibition of root growth. Our data indicate that salt stress interferes with cell cycle regulation at the transcriptional level, resulting in an adaptive growth response.
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PMID:Expression of cell cycle regulatory genes and morphological alterations in response to salt stress in Arabidopsis thaliana. 1108 75


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