Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A degenerative oligodeoxyribonucleotide probe deduced from the first 19 amino acids of the mature alkaline phosphatase IV (APase IV) protein was used to clone a DNA fragment internal to the coding region of the phoAIV gene of Bacillus subtilis. An insertional mutation was constructed in the phoAIV locus using the integrative plasmid, pJM103, containing the cloned DNA fragment. The strain with the interrupted phoAIV gene showed no detectable APase IV product on Western-blot analysis. The impact of the phoAIV interruption on total APase production in B. subtilis 168 was analyzed under both phosphate starvation and sporulation culturing conditions. The mutation in phoAIV reduced total APase-specific activity by 75% in phosphate-starved cells, and resulted in the elimination of a salt-extractable membrane APase, as well as the secreted APase IV. Analysis of this membrane APase indicated that it is a phoAIV gene product which is localized within the membrane fraction of the lysed cell and not secreted. There was no effect on the production of sporulation APase. The phoAIV::pJM103 insertion was mapped and determined to be located at approx. 73 degrees on the B. subtilis 360 degrees chromosome.
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PMID:The Bacillus subtilis phoAIV gene: effects of in vitro inactivation on total alkaline phosphatase production. 212 17

One of the signals that has been reported to be important in stimulating fruiting body formation of Myxococcus xanthus is starvation for phosphate. We therefore chose to study phosphatase activity during M. xanthus development. Many phosphatases can cleave the substrate p-nitrophenol phosphate. Using this substrate in buffers at various pHs, we obtained a profile of phosphatase activities during development and germination of M. xanthus. These experiments indicated that there are five patterns of phosphatase activity in M. xanthus: two vegetative and three developmental. The two uniquely vegetative activities have pH optima at 7.2 and 8.5. Both require magnesium and both are inhibited by the reducing agent dithiothreitol. The developmental (spores) patterns of activity have pH optima of 5.2, 7.2, and 8.5. All three activities are Mg independent. Only the alkaline phosphatase activity is inhibited by dithiothreitol. The acid phosphatase activity is induced very early in development, within the first 2 to 4 h. Both the neutral and alkaline phosphatase Mg-independent activities are induced much later, about the time that myxospores become evident (24 to 30 h). The three activities are greatly diminished upon germination; however, the kinetics of loss differ for all three. The acid phosphatase activity declines very rapidly, the neutral activity begins to decline only after spores begin to convert to rods, and the alkaline phosphatase activity remains high until the time the cells begin to divide. All three developmental activities were measured in the developmental signalling mutants carrying asg, csg, and dsg. The pattern of expression obtained in the mutants was consistent with that of other developmentally regulated genes which exhibit similar patterns of expression during development. The ease with which phosphatases can be assayed should make the activities described in this report useful biochemical markers of stages of both fruiting body formation and germination.
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PMID:Alkaline, acid, and neutral phosphatase activities are induced during development in Myxococcus xanthus. 215 68

Most of the essential cellular components, like nucleic acids, lipids and sugars, are phosphorylated. The phosphate equilibrium in Escherichia coli is regulated by the phosphate (Pi) input from the surrounding medium. Some 90 proteins are synthesized at an increased rate during Pi starvation and the global control of the cellular metabolism requires cross-talk with other regulatory mechanisms. Since the Pi concentration is normally low in E. coli's natural habitat, these cells have devised a mechanism for synthesis of about 15 proteins to accomplish two specific functions: transport of Pi and its intracellular regulation. The synthesis of these proteins is controlled by two genes (the phoB-phoR operon), involving both negative and positive functions. PhoR protein is a histidine protein kinase, induced in Pi starvation and is a transmembrane protein. It phosphorylates the regulator protein PhoB which is also Pi starvation-induced. The PhoB phosphorylated form binds specifically to a DNA sequence of 18 nucleotides (the pho Box), which is part of the promoters of the Pho genes. The genes controlled by phoB constitute the Pho regulon. The repression of phoA (the gene encoding alkaline phosphatase) by high Pi concentrations in the medium requires the presence of an intact Pst operon (pstS, pstC, pstA, pstB and phoU) and phoR. The products of pstA and pstC are membrane bound, whereas the product of pstS is periplasmic and PstB and PhoU proteins are cytoplasmic. The function of the PhoU protein may be regulated by cofactor nucleotides and may be involved in signaling the activation of the regulon via PhoR.
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PMID:From cell membrane to nucleotides: the phosphate regulon in Escherichia coli. 224 34

The clonal cell line HT29-D4 is able to differentiate by two different ways: i) by replacing glucose by galactose in the culture medium; ii) by addition of suramin (a drug known to interfere with the growth promoting activity of growth factors) in the medium. In both cases the transition in the organization of the cell monolayer occurred without cell loss. The two ways (i.e., glucose starvation or suramin addition) lead to polarized cells which generate electrically active cell monolayers (Fantini et al., Biol. Cell 65, 163-169 (1989) and this paper). Yet several important differences can be observed at the morphological or at the electrophysiological levels. 1) The suramin-treated cells (HT29-D4-S cells) organized into monolayers of high (40-50 microns) columnar cells while glucose-starved cells (HT29-D4-Gal cells) were rather cuboidal (20-25 microns). 2) HT29-D4-S cells were highly polarized; the nucleus was rejected at the basal side of the cell and lysosomes in the upper part of the cytoplasm. Numerous lipid-like droplets surrounded with glycogen were observed underneath the nucleus. HT29-D4-Gal cells never presented such a degree of organization. 3) The transepithelial resistance and the potential difference of HT29-D4-S monolayers reached values significantly higher than those for HT29-D4-Gal monolayers, reflecting a higher degree of organization. Specific proteins such as sucrase-isomaltase, alkaline phosphatase and carcinoembryonic antigen were localized exclusively on the apical membrane while human lymphocyte antigen (HLA) class I molecules were restricted to the basolateral membrane for both HT29-D4-S and HT29-D4-Gal cells. The present data demonstrate that the same cells can generate a different degree of cellular organization according to the experimental conditions of cell growth, the most elaborate state of differentiation being obtained in the presence of suramin.
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PMID:Suramin-treated HT29-D4 cells grown in the presence of glucose in permeable culture chambers form electrically active epithelial monolayers. A comparative study with HT29-D4 cells grown in the absence of glucose. 232 32

The phoA503 mutant was identified as a mutant that shows a novel phoA regulatory phenotype. The phoA503 allele dramatically reduces the synthesis of bacterial alkaline phosphatase activity during Pi starvation in an otherwise wild-type host and during the logarithmic growth phase in a phoR or phoU background. Near-normal amounts of enzyme activity are found in phoR phoA503 or phoU phoA503 mutants when starved for carbon, nitrogen, or sulfur or during the stationary phase, however. Marker rescue and DNA sequence analysis located the phoA503 mutation to the phoA coding region. It is a C-to-T transition that would cause a substitution of Val for Ala-22 in the mature protein. Transcriptional and translational lacZ fusions to both wild-type and mutant alleles demonstrated that phoA gene expression is unaltered. Also, the mutant protein was secreted and processed as efficiently as the wild type. Furthermore, the subunits appeared to dimerize and to be stable in the periplasm. But, greater than 98% of the dimers were inactive and found exclusively as isozyme 1. An activation of preformed phoA503 dimers occurred during the stationary phase with the concomitant conversion into isozymes 2 and 3. We propose that the phoA503 mutation affects a late stage in the formation of active enzyme. An unknown change when Pi is present during stationary-phase growth leads to formation of active dimers, which is responsible for this new conditional phenotype.
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PMID:A phoA structural gene mutation that conditionally affects formation of the enzyme bacterial alkaline phosphatase. 234 42

Phosphorylation of the insulin receptor beta-subunit on serine/threonine residues by protein kinase C reduces both receptor kinase activity and insulin action in cultured cells. Whether this mechanism regulates insulin action in intact animals was investigated in rats rendered insulin-resistant by 3 days of starvation. Insulin-stimulated autophosphorylation of the partially purified hepatic insulin receptor beta-subunit was decreased by 45% in starved animals compared to fed controls. This autophosphorylation defect was entirely reversed by removal of pre-existing phosphate from the receptor with alkaline phosphatase, suggesting that increased basal phosphorylation on serine/threonine residues may cause the decreased receptor tyrosine kinase activity. Tryptic removal of a C-terminal region of the receptor beta-subunit containing the Ser/Thr phosphorylation sites similarly normalized receptor autophosphorylation. To investigate which kinase(s) may be responsible for such increased Ser/Thr phosphorylation in vivo, protein kinase C and cAMP-dependent protein kinase A in liver were studied. A 2-fold increase in protein kinase C activity was found in both cytosol and membrane extracts from starved rats as compared to controls, while protein kinase A activity was diminished in the cytosol of starved rats. A parallel increase in protein kinase C was demonstrated by immunoblotting with a polyclonal antibody which recognizes several protein kinase C isoforms. These findings suggest that in starved, insulin-resistant animals, an increase in hepatic protein kinase C activity is associated with increased Ser/Thr phosphorylation which in turn decreases autophosphorylation and function of the insulin receptor kinase.
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PMID:Increased protein kinase C activity is linked to reduced insulin receptor autophosphorylation in liver of starved rats. 235 98

We reviewed retrospectively a cohort of 80 patients with hyperemesis gravidarum hospitalized between 1976 and 1986 for the presence of abnormal liver enzymes and ketonuria. Thirteen (16%) had abnormal liver enzymes, generally less than four times the upper limit of normal. In this group, hyperemesis gravidarum began at the 14th week of pregnancy as compared to the 6th week in the normal enzyme group (p less than 0.01). Both groups were similar with regard to age, number of children and pregnancies, and duration of vomiting. Ketonuria was significantly more severe (p less than 0.01) in the abnormal enzyme group, implying a more severe state of starvation and dehydration. The correlation coefficient between the degree of ketonuria and level of liver enzymes was low for alkaline phosphatase (r = 0.18), GPT (r = 0.15), and GOT (r = 0.28). The concept that dehydration and starvation are important factors for the induction of liver cell injury is supported by our data. Lack of correlation between the degree of ketonuria and liver enzyme levels is suggestive of other mechanisms (hormonal, genetic) that may interact to produce transaminasemia.
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PMID:Abnormal liver enzymes and ketonuria in hyperemesis gravidarum. A retrospective review of 80 patients. 236 99

The phoR gene product functions as a negative regulator with excess of phosphate and as a positive regulator with limited phosphate for the phosphate-starvation-inducible pho regulon of Escherichia coli. We constructed recombinant plasmids that contain a phoR'-'lacZ fusion gene to study the regulation of phoR expression. The genetic and physiological regulation of phoR expression was found to be very similar to that of phoB, a positive regulatory gene for the pho regulon, and phoA, the structural gene for alkaline phosphatase, both of which are inducible by phosphate limitation. The synthesis of the PhoR protein became non-inducible when the phoB promoter upstream of phoR, was removed from the hybrid plasmid, or when a transcriptional terminator was inserted in the phoB structural gene, irrespective of phosphate concentration in the medium. The results suggest that phoB and phoR constitute a single operon whose promoter is located proximal to phoB. The same low level of the PhoR protein in the cell can function as a positive regulator with limited phosphate and as a negative regulator with excess phosphate for the phoB-phoR operon. These results suggest that the maximal level of the operon is induced as consequences of both the increase in the quantity of the PhoR protein and of functional change of the protein as a positive regulator, which are induced by phosphate limitation.
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PMID:Regulation of the phosphate regulon of Escherichia coli K-12: regulation and role of the regulatory gene phoR. 241 41

A recombinant plasmid carrying a bovine growth hormone gene fused with the regulatory and signal regions of the alkaline phosphatase gene of E. coli was constructed. The bovine growth hormone gene expression as well as protein partial processing and secretion into the periplasm have been shown to take place under phosphate starvation, i.e. conditions of alkaline phosphatase derepression.
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PMID:[Biosynthesis and secretion of bovine growth hormone in Escherichia coli under the control of the secretory vector containing a promoter and signal region of the alkaline phosphatase gene]. 267 71

The effect of starvation and sampling time on plasma alkaline phosphatase activity, total plasma calcium concentration and whole blood ionized calcium concentration was determined in the rat. Starvation caused a significant fall in total and ionized calcium concentrations as well as in alkaline phosphatase activity. These changes were accompanied by a fall in whole blood pH and an increase in the anion gap and a decrease in urinary excretion of calcium. These indices were restored to normal following refeeding. There was no change in serum 25-OH vitamin D concentrations following starvation for 3 days. Alkaline phosphatase activity showed a pattern compatible with the presence of a circadian rhythm when sampling took place between 0800 and 1800 h. Total and ionized calcium concentrations did not show such a rhythm when animals were fed the present diet.
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PMID:Effect of starvation and sampling time on plasma alkaline phosphatase activity and calcium homeostasis in the rat. 278 12


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