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)

A rice gene encoding a calcium-dependent protein kinase (CDPK), OsCDPK7, was induced by cold and salt stresses. To elucidate the physiological function of OsCDPK7, we generated transgenic rice plants with altered levels of the protein. The extent of tolerance to cold and salt/drought stresses of these plants correlated well with the level of OsCDPK7 expression. Therefore, OsCDPK7 was shown to be a positive regulator commonly involved in the tolerance to both stresses in rice. Over-expression of OsCDPK7 enhanced induction of some stress-responsive genes in response to salinity/drought, but not to cold. Thus, it was suggested that the downstream pathways leading to the cold and salt/drought tolerance are different from each other. It seems likely that at least two distinct pathways commonly use a single CDPK, maintaining the signalling specificity through unknown post-translational regulation mechanisms. These results demonstrate that simple manipulation of CDPK activity has great potential with regard to plant improvement.
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PMID:Over-expression of a single Ca2+-dependent protein kinase confers both cold and salt/drought tolerance on rice plants. 1092 25

The influence of phosphorylation on the properties of lactate dehydrogenase (LDH) has been studied. Data obtained using the immobilization approach support the assumption that the autophosphorylation of LDH discovered previously in the presence of ATP has no relation to protein kinase activity of the enzyme. Phosphorylation of native LDH by tyrosine kinases was shown to be inefficient. However, the efficiency of the phosphorylation considerably increased after the dissociation of LDH into non-native forms of the enzyme. Ca2+/calmodulin-dependent protein kinase catalyzes incorporation of 0.8-0.9 mole phosphate per mole of LDH tetramer. The phosphorylation results in an increase in activity by 25-30% and increases markedly the stability of the enzyme during cold inactivation. Phosphorylation of LDH by Ca2+/calmodulin-dependent protein kinase, unlike the phosphorylation on tyrosine residues, is supposed to be of importance for the control of cell metabolism.
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PMID:Phosphorylation of lactate dehydrogenase by protein kinases. 1109 63

The Aspergillus nidulans NIMX(CDC2) protein kinase has been shown to be required for both the G(2)/M and G(1)/S transitions, and recent evidence has implicated a role for NIMX(CDC2) in septation and conidiation. While much is understood of its G(2)/M function, little is known about the functions of NIMX(CDC2) during G(1)/S, septation, and conidiophore development. In an attempt to better understand how NIMX(CDC2) is involved in these processes, we have isolated four extragenic suppressors of the A. nidulans nimX2(cdc2) temperature-sensitive mutation. Mutation of these suppressor genes, designated snxA-snxD for suppressor of nimX, affects nuclear division, septation, and conidiation. The cold-sensitive snxA1 mutation leads to arrest of nuclear division during G(1) or early S. snxB1 causes hyperseptation in the hyphae and sensitivity to hydroxyurea, while snxC1 causes septation in the conidiophore stalk and aberrant conidiophore structure. snxD1 leads to slight septation defects and hydroxyurea sensitivity. The additional phenotypes that result from the suppressor mutations provide genetic evidence that NIMX(CDC2) affects septation and conidiation in addition to nuclear division, and cloning and biochemical analysis of these will allow a better understanding of the role of NIMX(CDC2) in these processes.
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PMID:Extragenic suppressors of the nimX2(cdc2) mutation of Aspergillus nidulans affect nuclear division, septation and conidiation. 1110 58

Removal of Ca(2+) from tobacco suspension cell medium has two immediate effects on cytosolic Ca(2+) fluxes: (i) externally derived Ca(2+) influx (occurring in response to cold shock or hypo-osmotic shock) is inhibited, and (ii) organellar Ca(2+) release (induced by a fungally derived defense elicitor, caffeine, or hypo-osmotic shock) is elevated. We show here that the enhanced release of internal Ca(2+) is likely due to increased discharge from a caffeine-sensitive store in response to a signal transduced from an extracellular Ca(2+) sensor. Thus, chelation of extracellular Ca(2+) in the absence of any other stimulus directly activates release of intracellular Ca(2+) into the cytosol. Evidence that this chelator-activated Ca(2+) flux is dependent on a signaling pathway includes its abrogation by prior treatment with caffeine, and its inhibition by protein kinase inhibitors (K252a and staurosporine) and anion channel blockers (niflumate and anthracene-9-carboxylate). An unexpected characteristic of tobacco cell adaptation to low external Ca(2+) was the emergence of a new Ca(2+) compartment that was inaccessible to external EGTA, yet responsive to the usual stimulants of extracellular Ca(2+) entry. Thus, cells that are exposed to EGTA for 20 min lose sensitivity to caffeine and defense elicitors, indicating that their intracellular Ca(2+) pools have been depleted. Surprisingly, these same cells simultaneously regain their ability to respond to stimuli that usually activate extracellular Ca(2+) influx even though all external Ca(2+) is chelated. Because this gradual restoration of Ca(2+) influx can be inhibited by the same kinase inhibitors that block EGTA-activated Ca(2+) release, we propose that chelator-activated Ca(2+) release from internal stores leads to deposition of this Ca(2+) into a novel EGTA- and caffeine-insensitive compartment that can subsequently be activated by stimulants of extracellular Ca(2+) entry.
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PMID:An apoplastic Ca2+ sensor regulates internal Ca2+ release in aequorin-transformed tobacco cells. 1113 70

The CREM (cAMP-response-element modulator) gene product ICER (induced cAMP early repressor) has been proposed to function as a tumour (cell proliferation) suppressor. To investigate the generality of this concept, the expression pattern of ICER in brown adipocytes was followed; this was critical because brown adipocytes are one of few cell types in which cAMP is associated positively with cell proliferation but negatively with apoptosis. In response to the physiological stimulus of cold (which induces cell proliferation), ICER mRNA levels were increased in brown adipose tissue in vivo. In brown adipocytes in primary culture, ICER gene expression was induced by noradrenaline (norepinephrine) not only in the mature state (where noradrenaline potentiates differentiation), but also in the proliferative state of the cell cultures (where noradrenaline enhances cell proliferation). The induction was mediated via beta-receptors and the cAMP/protein kinase A pathway. The induced ICER appeared to repress its own expression and that of the beta2-adrenoceptor. It is thus evident that also in cell types in which cAMP induces proliferation, and even when these cells are in the proliferative state, ICER expression is induced by the same agents that stimulate proliferation. This can either mean that ICER is not a general tumour suppressor, or that brown adipocytes temporally or spatially avoid this role of ICER.
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PMID:As the proliferation promoter noradrenaline induces expression of ICER (induced cAMP early repressor) in proliferative brown adipocytes, ICER may not be a universal tumour suppressor. 1117 Oct 92

The relationship between the platelet storage lesion (PSL) and programmed cell death (apoptosis) is poorly understood. Nevertheless, there is some experimental evidence that platelets contain most of the components of the apoptosis machinery and both the apoptotic process and the PSL lead to platelet activation and microvesiculation with expression of phosphatidyl serine (PS) on the outer layer of cell membrane, a hallmark of all nucleated cells. The PS exposure is believed to contribute to the development of inflammatory or immunomodulation process, to the regulation of haemostatic balance and the ultimate clearance of dead or fragmented cells from the circulation. While there is no doubt that apoptosis, as a form of genetically encoded programmed cell death in nucleated cells, is triggered by several signalling stimuli at the nuclear level, there is some doubt as to whether platelets, as enucleated cells have retained the memory of the "parental" megakaryocytes for apoptosis or whether platelet mitochondrial DNA has a major role in both the apoptotic process and the PSL. The storage lesion occurs during processing and storage subsequent to mechanical trauma, hypoxic conditions or exposure to cold. In this brief report some observational evidence is provided in support of the notion that the PSL and apoptosis may be related to each other, despite the fact that, in contrast to the 'parental' megakarocyte, the platelets appear to survive upon stimulation with a high concentration of protein kinase inhibitors such as staurosporine (STS), in the presence of cycloheximide (CHX) which inhibit protein synthesis. This is a model which is often used to regulate the level of survival signals. The possible relevance of platelet microvesiculation to transfusion practice is briefly discussed.
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PMID:Platelet storage lesion and apoptosis: are they related? 1151 5

Forward genetics and biochemical approaches to studying plant responses to salt, water and cold stresses began to bear fruit recently. Analysis of salt overly sensitive (sos) Arabidopsis mutants revealed a novel calcium-regulated protein kinase pathway for response to the ionic aspect of salt stress. In-gel kinase assays identified several SOS-independent protein kinases that are either activated specifically by osmotic stress or by multiple abiotic and biotic stresses. Molecular analysis revealed a transcriptional cascade in cold-regulated gene expression.
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PMID:Cell signaling under salt, water and cold stresses. 1159 97

Ded1 is a fission yeast DEAD box protein involved in translation. We isolated Ded1 in a screen for multi-copy suppressors of a cold-sensitive, loss-of-function mutant of the cyclin-dependent kinase Cdc2. The checkpoint protein kinase Chk1, required for cell cycle arrest in response to DNA damage, was also isolated in this screen. Ded1 interacts with Chk1 in a two-hybrid screen, and this physical interaction can be recapitulated in Schizosaccharomyces pombe. The Ded1 polypeptide is modified in response to heat shock and depletion of carbon source. These two stressors appear to cause different modifications. Thus, the Ded1 protein appears to respond to particular types of cellular stress and may influence the activity of Cdc2 as a result.
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PMID:The Ded1 DEAD box helicase interacts with Chk1 and Cdc2. 1171 40

The Ca2+-dependent protein kinases (CDPKs) and abscisic acid (ABA) are known to be involved in low-temperature stress response. The focus of this study was to characterize the 45 kDa protein kinase identified in the crude extract of rice (Oryza sativa L.) seedling roots in response to cold (5 degrees C) stress. The activity of the 45 kDa protein kinase decreased at low temperature as evident by an in-gel kinase assay using histone III-S as a substrate. Also, the Ca2+-dependent activity of this protein kinase was suppressed by cold in the membrane fractions of the root. A general protein kinase inhibitor and Ca2+ chelator inhibited the activity of the 45 kDa protein kinase, suggesting that it was a plant CDPK. The 45 kDa CDPK identified was found to be independent of photosynthetic tissues such as the leaf and leaf sheath of rice seedlings, supporting a direct sensing mechanism in the roots of rice seedlings to cold stress. The suppressed activity of the 45 kDa CDPK was reverted by supplementing with 5 microM ABA under cold stress. The 45 kDa CDPK activity was stronger in the cold-tolerant variety of the 4 types tested than it was in the cold-sensitive one. These results suggest the involvement of endogenous ABA in regulating the activity of the 45 kDa CDPK in response to cold stress.
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PMID:Characterization of a Ca2+-dependent protein kinase from rice root: differential response to cold and regulation by abscisic acid. 1172 71

A rice Ca(2+)-dependent protein kinase, OsCDPK7, is a positive regulator commonly involved in the tolerance to cold and salt/drought. We carried out in situ detection of the transcript and immunolocalization of the protein. In the wild-type rice plants under both stress conditions, OsCDPK7 was expressed predominantly in vascular tissues of crowns and roots, vascular bundles and central cylinder, respectively, where water stress occurs most severely. This enzyme was also expressed in the peripheral cylinder of crown vascular bundles and root sclerenchyma. Similar localization patterns with stronger signals were observed in stress-tolerant OsCDPK7 over-expressing transformants with the cauliflower mosaic virus 35S promoter. The transcript of a putative target gene of the OsCDPK7 signaling pathway, rab16A, was also detected essentially in the same tissues upon salt stress, suggesting that the OsCDPK7 pathway operates predominantly in these regions. We propose that the use of the 35S promoter fortuitously strengthened the localized expression of OsCDPK7, resulting in enhancement of the stress signaling in the inherently operating regions leading to improved stress tolerance.
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PMID:A Ca(2+)-dependent protein kinase that endows rice plants with cold- and salt-stress tolerance functions in vascular bundles. 1172 7


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