scholarly journals The quantitative spectrum of inositol phosphate metabolites in avian erythrocytes, analysed by proton n.m.r. and h.p.l.c. with direct isomer detection

1989 ◽  
Vol 264 (2) ◽  
pp. 323-333 ◽  
Author(s):  
T Radenberg ◽  
P Scholz ◽  
G Bergmann ◽  
G W Mayr
Keyword(s):  
Mammalian Cells ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Detection System ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Phosphate Metabolism ◽  
Qualitative And Quantitative ◽  
Inositol Phosphate Metabolism ◽  
Avian Erythrocytes

The spectrum of inositol phosphate isomers present in avian erythrocytes was investigated in qualitative and quantitative terms. Inositol phosphates were isolated in micromolar quantities from turkey blood by anion-exchange chromatography on Q-Sepharose and subjected to proton n.m.r. and h.p.l.c. analysis. We employed a h.p.l.c. technique with a novel, recently described complexometric post-column detection system, called ‘metal-dye detection’ [Mayr (1988) Biochem. J. 254, 585-591], which enabled us to identify non-radioactively labelled inositol phosphate isomers and to determine their masses. The results indicate that avian erythrocytes contain the same inositol phosphate isomers as mammalian cells. Denoted by the ‘lowest-locant rule’ [NC-IUB Recommendations (1988) Biochem. J. 258, 1-2] irrespective of true enantiomerism, these are Ins(1,4)P2, Ins(1,6)P2, Ins(1,3,4)P3, Ins(1,4,5)P3, Ins(1,3,4,5)P4, Ins(1,3,4,6)P4, Ins(1,4,5,6)P4, Ins(1,3,4,5,6)P5, and InsP6. Furthermore, we identified two inositol trisphosphate isomers hitherto not described for mammalian cells, namely Ins(1,5,6)P3 and Ins(2,4,5)P3. The possible position of these two isomers in inositol phosphate metabolism and implications resulting from absolute abundances of inositol phosphates are discussed.

Synthesis of inositol phosphate ligands of plant hormone–receptor complexes: pathways of inositol hexakisphosphate turnover

2012 ◽  
Vol 444 (3) ◽  
pp. 601-609 ◽  
Author(s):  
David E. Hanke ◽  
Paroo N. Parmar ◽  
Samuel E. K. Caddick ◽  
Porntip Green ◽  
Charles A. Brearley
Keyword(s):  
Hormone Receptor ◽  
Plant Hormone ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Leaf Tissue ◽  
Phosphate Metabolism ◽  
Inositol Hexakisphosphate ◽  
Receptor Complexes ◽  
Inositol Phosphate Metabolism ◽  
Phosphate Ligands

Reduction of phytate is a major goal of plant breeding programs to improve the nutritional quality of crops. Remarkably, except for the storage organs of crops such as barley, maize and soybean, we know little of the stereoisomeric composition of inositol phosphates in plant tissues. To investigate the metabolic origins of higher inositol phosphates in photosynthetic tissues, we have radiolabelled leaf tissue of Solanum tuberosum with myo-[2-3H]inositol, undertaken a detailed analysis of inositol phosphate stereoisomerism and permeabilized mesophyll protoplasts in media containing inositol phosphates. We describe the inositol phosphate composition of leaf tissue and identify pathways of inositol phosphate metabolism that we reveal to be common to other kingdoms. Our results identify the metabolic origins of a number of higher inositol phosphates including ones that are precursors of cofactors, or cofactors of plant hormone–receptor complexes. The present study affords alternative explanations of the effects of disruption of inositol phosphate metabolism reported in other species, and identifies different inositol phosphates from that described in photosynthetic tissue of the monocot Spirodela polyrhiza. We define the pathways of inositol hexakisphosphate turnover and shed light on the occurrence of a number of inositol phosphates identified in animals, for which metabolic origins have not been defined.

scholarly journals The labelling of polyphosphoinositides with [32P]Pi and the accumulation of inositol phosphates in vasopressin-stimulated hepatocytes

1986 ◽  
Vol 238 (2) ◽  
pp. 491-499 ◽  
Author(s):  
S Palmer ◽  
P T Hawkins ◽  
R H Michell ◽  
C J Kirk
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Water Soluble ◽  
Ionophore A23187 ◽  
Inositol Tetrakisphosphate ◽  
Inositol Phosphate Accumulation ◽  
Phosphatidylinositol 4 ◽  
Phosphate Groups

When hepatocytes were incubated with [32P]Pi, the kinetics for the labelling of the monoester phosphate groups of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate were similar to each other and slightly slower than that for the labelling of the gamma-phosphate of ATP. Analysis of the water-soluble 3H-labelled materials derived from [3H]inositol-labelled hepatocytes revealed that, in addition to inositol and its mono-, bis- and tris-phosphates (Ins, InsP, InsP2 and InsP3), these cells contained two unidentified radioactive compounds which co-eluted with InsP on anion-exchange chromatography. When [3H]inositol-labelled hepatocytes were stimulated with 0.23 microM-vasopressin in the presence of 10 mM-Li+, there was an accumulation of radioactivity in InsP, InsP2 and InsP3 but not in Ins or the two unidentified compounds. Further analysis of these inositol phosphates by h.p.l.c. revealed that vasopressin also stimulates the accumulation of inositol tetrakisphosphate (InsP4) in these cells. Vasopressin-stimulated InsP and InsP2 accumulations were maximal in the presence of 1-10 mM-Li+ but InsP3 accumulation continued to increase up to 50 mM-Li+. Accumulated inositol phosphates were retained within the cell. Li+ from 1 to 50 mM did not influence the extent of vasopressin-stimulated inositol lipid degradation in hepatocytes. In the absence of Li+, radioactivity in vasopressin-stimulated hepatocytes accumulated almost entirely in free inositol. The vasopressin-stimulated accumulation of inositol phosphates in the presence of 10 mM-Li+ was abolished by a V1-vasopressin antagonist. Inositol phosphate accumulation was not influenced by ionophore A23187, dimethyl sulphoxide or indomethacin.

scholarly journals Guanosine 5′-[γ-thio]triphosphate-stimulated hydrolysis of phosphatidylinositol 4,5-bisphosphate in HL-60 granulocytes. Evidence that the guanine nucleotide acts by relieving phospholipase C from an inhibitory constraint

1990 ◽  
Vol 271 (3) ◽  
pp. 743-748 ◽  
Author(s):  
M Camps ◽  
C F Hou ◽  
K H Jakobs ◽  
P Gierschik
Keyword(s):  
Phospholipase C ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Anion Exchange Chromatography ◽  
Major Product ◽  
Exchange Chromatography ◽  
High Protein ◽  
High Protein Concentration ◽  
Inositol Phosphate Accumulation ◽  
Stimulation Of

Myeloid differentiated human leukaemia (HL-60) cells contain a soluble phospholipase C that hydrolysed phosphatidylinositol 4.5-bisphosphate and was markedly stimulated by the metabolically stable GTP analogue guanosine 5′-[gamma-thio]triphosphate (GTP[S]). Half-maximal and maximal (up to 5-fold) stimulation of inositol phosphate formation by GTP[S] occurred at 1.5 microM and 30 microM respectively. Other nucleotides (GTP, GDP, GMP, guanosine 5′-[beta-thio]diphosphate. ATP, adenosine 5′-[gamma-thio]triphosphate, UTP) did not affect phospholipase C activity, GTP[S] stimulation of inositol phosphate accumulation was inhibited by excess GDP, but not by ADP. The effect of GTP[S] on inositol phosphate formation was absolutely dependent on and markedly stimulated by free Ca2+ (median effective concn. approximately 100 nM). Analysis of inositol phosphates by anion-exchange chromatography revealed InsP3 as the major product of GTP[S]-stimulated phospholipase C activity. In the absence of GTP[S], specific phospholipase C activity was markedly decreased when tested at high protein concentrations, whereas GTP[S] stimulation of the enzyme was markedly enhanced under these conditions. As both basal and GTP[S]-stimulated inositol phosphate formation were linear with time whether studied at low or high protein concentration, these results suggest that (a) phospholipase C is under an inhibitory constraint and (b) GTP[S] relieves this inhibition, most likely by activating a soluble GTP-binding protein.

scholarly journals Agonist-stimulated inositol phosphate metabolism in avian erythrocytes

1990 ◽  
Vol 269 (1) ◽  
pp. 65-72 ◽  
Author(s):  
L R Stephens ◽  
C P Berrie ◽  
R F Irvine
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Specific Radioactivity ◽  
Intact Cells ◽  
Inositol Phosphate Metabolism ◽  
Avian Erythrocytes ◽  
32P Incorporation ◽  
The Individual ◽  
Chicken Erythrocytes ◽  
Purinergic Stimulation

1. A screen for agonists capable of stimulating the formation of inositol phosphates in erythrocytes from 5-day-old chickens revealed the presence of a population of phosphoinositidase C-linked purinergic receptors. 2. If chicken erythrocytes prelabelled with [3H]Ins were exposed to a maximal effective dose of adenosine 5′-[beta-thio]diphosphate for 30 s, the agonist-stimulated increment in total [3H]inositol phosphates was confined to [3H]Ins(1,4,5)P3, Ins(1,3,4,5)P4 and InsP2. After 40 min stimulation, the radiolabelling of nearly all of the [3H]inositol phosphates that have been detected in these extracts [Stephens, Hawkins & Downes (1989) Biochem. J. 262, 727-737] had risen. However, some of these increases [especially those in Ins(3,4,5,6)P4 and Ins(1,3,4,5,6)P5] were accountable for almost entirely by increases in specific radioactivity rather than in mass. 3. The effect of purinergic stimulation on the rate of incorporation of [32P]Pi in the medium into the gamma-phosphate group of ATP and InsP4 and InsP5 was also measured. After 40 min stimulation, the incorporation of 32P into Ins(1,3,4,6)P4, Ins(1,3,4,5)P4, Ins(3,4,5,6)P4 and Ins(1,3,4,5,6)P5 was significantly elevated, whereas the mass of the last two and the specific radioactivity of the gamma-phosphate of ATP were unchanged compared with control erythrocyte suspensions. 4. In control suspensions of avian erythrocytes, the specific radioactivity of the individual phosphate moieties of Ins(1,3,4,6)P4 increased through the series 1, 6, 4 and 3 [Stephens & Downes (1990) Biochem. J. 265, 435-452]. This pattern of 32P incorporation is not the anticipated outcome of 6-hydroxy phosphorylation of Ins(1,3,4)P3 [the assumed route of synthesis of Ins(1,3,4,6)P4]. Although adenosine [beta-thio]diphosphate significantly stimulated the accumulation of [3H]Ins(1,3,4)P3, and despite the fact that avian erythrocyte lysates were shown to possess a chromatographically distinct, soluble, ATP-dependent, Ins(1,3,4)P3 6-hydroxykinase activity, purinergic stimulation of intact cells did not significantly alter the pattern of incorporation of [32P]Pi into the individual phosphate moieties of Ins(1,3,4,6)P4. These results suggest that the route of synthesis of this inositol phosphate species is not changed during the presence of an agonist.

scholarly journals Arabidopsis inositol phosphate kinases, IPK1 and ITPK1, constitute a metabolic pathway in maintaining phosphate homeostasis

2018 ◽  
Author(s):  
Hui-Fen Kuo ◽  
Yu-Ying Hsu ◽  
Wei-Chi Lin ◽  
Kai-Yu Chen ◽  
Teun Munnik ◽  
...  
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Phosphate Limitation ◽  
Phosphate Metabolism ◽  
Adaptive Responses ◽  
Phosphate Homeostasis ◽  
Close Link ◽  
Inositol Phosphate Metabolism ◽  
Evolutionarily Conserved ◽  
Specific Increase

SummaryEmerging studies have implicated a close link between inositol phosphate (InsP) metabolism and cellular phosphate (Pi) homeostasis in eukaryotes; however, whether a common InsPspecies is deployed as an evolutionarily conserved metabolic messenger to mediate Pisignaling remains unknown. Here, using genetics and InsPprofiling combined with Pistarvation response (PSR) analysis inArabidopsis thaliana, we showed that the kinase activity of inositol pentakisphosphate 2-kinase (IPK1), an enzyme required for phytate (inositol hexakisphosphates; InsP6) synthesis, is indispensable for maintaining Pihomeostasis under Pi-replete conditions, and inositol 1,3,4-trisphosphate 5/6-kinase 1 (ITPK1) plays an equivalent role. Although bothipk1-1anditpk1mutants exhibited decreased levels of InsP6and diphosphoinositol pentakisphosphate (PP-InsP5; InsP7), disruption of another ITPK family enzyme, ITPK4, which correspondingly caused depletion of InsP6and InsP7, did not display similar Pi-related phenotypes, which precludes these InsPspecies as effectors. Notably, the level of D/L-Ins(3,4,5,6)P4was concurrently elevated in bothipk1-1anditpk1mutants, which implies a potential role for InsP4in regulating Pihomeostasis. However, the level of D/L-Ins(3,4,5,6)P4is not responsive to Pistarvation that instead manifests a shoot-specific increase in InsP7level. This study demonstrates a more nuanced picture of intersection of InsPmetabolism and Pihomeostasis and PSR than has previously been elaborated, and additionally establishes intermediate steps to phytate biosynthesis in plant vegetative tissues.Significance StatementRegulation of phosphate homeostasis and adaptive responses to phosphate limitation is critical for plant growth and crop yield. Accumulating studies implicate inositol phosphates as regulators of phosphate homeostasis in eukaryotes; however, the relationship between inositol phosphate metabolism and phosphate signaling in plants remain elusive. This study dissected the step where inositol phosphate metabolism intersects with phosphate homeostasis regulation and phosphate starvation responses.

scholarly journals Carbachol causes rapid phosphodiesteratic cleavage of phosphatidylinositol 4,5-bisphosphate and accumulation of inositol phosphates in rabbit iris smooth muscle; prazosin inhibits noradrenaline- and ionophore A23187-stimulated accumulation of inositol phosphates

1984 ◽  
Vol 224 (1) ◽  
pp. 291-300 ◽  
Author(s):  
R A Akhtar ◽  
A A Abdel-Latif
Keyword(s):  
Smooth Muscle ◽  
Time Course ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Ionophore A23187 ◽  
Release Of Noradrenaline ◽  
Adrenergic Blocker ◽  
Rabbit Iris

Rabbit iris smooth muscle was prelabelled with myo-[3H]inositol for 90 min and the effect of carbachol on the accumulation of inositol phosphates from phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol (PtdIns) was monitored with anion-exchange chromatography. Carbachol stimulated the accumulation of inositol phosphates and this was blocked by atropine, a muscarinic antagonist, and it was unaffected by 2-deoxyglucose. The data presented demonstrate that, in the iris, carbachol (50 microM) stimulates the rapid breakdown of PtdIns(4,5)P2 into [3H]inositol trisphosphate (InsP3) and diacylglycerol, measured as phosphatidate, and that the accumulation of InsP3 precedes that of [3H]inositol bisphosphate (InsP2) and [3H]inositol phosphate (InsP). This conclusion is based on the following findings. Time course experiments with myo-[3H]inositol revealed that carbachol increased the accumulation of InsP3 by 12% in 15s and by 23% in 30s; in contrast, a significant increase in InsP release was not observed until about 2 min. Time-course experiments with 32P revealed a 10% loss of radioactivity from PtdIns(4,5)P2 and a corresponding 10% increase in phosphatidate labelling by carbachol in 15s; in contrast a significant increase in PtdIns labelling occurred in 5 min. Dose-response studies revealed that 5 microM-carbachol significantly increased (16%) the accumulation of InsP3 whereas a significant increase in accumulation of InsP2 and InsP was observed only at agonist concentrations greater than 10 microM. Studies on the involvement of Ca2+ in the agonist-stimulated breakdown of PtdIns(4,5)P2 in the iris revealed the following. Marked stimulation (58-78%) of inositol phosphates accumulation by carbachol in 10 min was observed in the absence of extracellular Ca2+. Like the stimulatory effect of noradrenaline, the ionophore A23187-stimulated accumulation of InsP3 was inhibited by prazosin, an alpha 1-adrenergic blocker, thus suggesting that the ionophore stimulation of PtdIns(4,5)P2 breakdown we reported previously [Akhtar & Abdel-Latif (1978) J. Pharmacol. Exp. Ther. 204, 655-688; Akhtar & Abdel-Latif (1980) Biochem. J. 192, 783-791] was secondary to the release of noradrenaline by the ionophore. The carbachol-stimulated accumulation of inositol phosphates was inhibited by EGTA (0.25 mM) and this inhibition was reversed by excess Ca2+ (1.5 mM), suggesting that EGTA treatment of the tissue chelates extracellular Ca2+ required for polyphosphoinositide phosphodiesterase activity. K+ depolarization, which causes influx of extracellular Ca2+ in smooth muscle, did not change the level of InsP3.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential induction of inositol phosphate metabolism by three adipokinetic hormones

1997 ◽  
Vol 130 (1-2) ◽  
pp. 131-139 ◽  
Author(s):  
Simon F Vroemen ◽  
Wil J.A Van Marrewijk ◽  
Jeroen De Meijer ◽  
Aloys Th.M Van den Broek ◽  
Dick J Van der Horst
Keyword(s):  
Inositol Phosphate ◽  
Phosphate Metabolism ◽  
Inositol Phosphate Metabolism ◽  
Differential Induction

scholarly journals Analysis of Inositol Phosphate Metabolism by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry (CE-ESI-MS)

2020 ◽  
Author(s):  
Danye Qiu ◽  
Miranda S. Wilson ◽  
Verena B. Eisenbeis ◽  
Robert K. Harmel ◽  
Esther Riemer ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Capillary Electrophoresis ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Inositol Phosphate ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Phosphate Metabolism ◽  
Esi Ms ◽  
Inositol Phosphate Metabolism

AbstractThe analysis of myo-inositol phosphates (InsPs) and myo-inositol pyrophosphates (PP-InsPs) is a daunting challenge due to the large number of possible isomers, the absence of a chromophore, the high charge density, the low abundance, and the instability of the esters and anhydrides. Given their importance in biology, an analytical approach to follow and understand this complex signaling hub is highly desirable. Here, capillary electrophoresis (CE) coupled to electrospray ionization mass spectrometry (ESI-MS) is implemented to analyze complex mixtures of InsPs and PP-InsPs with high sensitivity. Stable isotope labeled (SIL) internal standards allow for matrix-independent quantitative assignment. The method is validated in wild-type and knockout mammalian cell lines and in model organisms. SIL-CE-ESI-MS enables for the first time the accurate monitoring of InsPs and PP-InsPs arising from compartmentalized cellular synthesis pathways, by feeding cells with either [13C6]-myo-inositol or [13C6]-D-glucose. In doing so, we uncover that there must be unknown inositol synthesis pathways in mammals, highlighting the unique potential of this method to dissect inositol phosphate metabolism and signalling.

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