Purification and Properties of myo-Inositol-1-Phosphatase from Rat Brain

Takimoto, K.; Okada, Masato; Matsuda, Yoshihisa; Nakagawa, Hachiro

doi:10.1093/oxfordjournals.jbchem.a135290

Cited by 87 publications

(74 citation statements)

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“…Mammalian inositol monophosphatases have been shown to have a relatively broad substrate specificity and can hydrolyze a variety of phosphate compounds other than inositol monophosphatase (6,7,11,16,24,37). For instance, the enzyme from rat testis hydrolyzes adenosine 2Ј-monophosphate with a relative velocity of 38% (6) and the enzyme from bovine brain hydrolyzes ␤-glycerophosphate and adenosine 2Ј-monophosphate with relative velocities of 33 and 50%, respectively (7).…”

Section: Resultsmentioning

confidence: 99%

Inositol monophosphatase activity from the Escherichia coli suhB gene product

et al. 1995

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The suhB gene is located at 55 min on the Escherichia coli chromosome and encodes a protein of 268 amino acids. Mutant alleles of suhB have been isolated as extragenic suppressors for the protein secretion mutation (secY24), the heat shock response mutation (rpoH15), and the DNA synthesis mutation (dnaB121) (K. Shiba, K. Ito, and T. Yura, J. Bacteriol. 160:696-701, 1984; R. Yano, H. Nagai, K. Shiba, and T. Yura, J. Bacteriol. 172:2124-2130, 1990; S. Chang, D. Ng, L. Baird, and C. Georgopoulos, J. Biol. Chem. 266:3654-3660, 1991). These mutant alleles of suhB cause cold-sensitive cell growth, indicating that the suhB gene is essential at low temperatures. Little work has been done, however, to elucidate the role of the product of suhB in a normal cell and the suppression mechanisms of the suhB mutations in the aforementioned mutants. The sequence similarity shared between the suhB gene product and mammalian inositol monophosphatase has prompted us to test the inositol monophosphatase activity of the suhB gene product. We report here that the purified SuhB protein showed inositol monophosphatase activity. The kinetic parameters of SuhB inositol monophosphatase (K m ‫؍‬ 0.071 mM; V max ‫؍‬ 12.3 mol/min per mg) are similar to those of mammalian inositol monophosphatase. The ssyA3 and suhB2 mutations, which were isolated as extragenic suppressors for secY24 and rpoH15, respectively, had a DNA insertion at the 5 proximal region of the suhB gene, and the amount of SuhB protein within mutant cells decreased. The possible role of suhB in E. coli is discussed.The suhB gene was first identified as the locus for the ssyA3(Cs) mutation that was isolated as an extragenic suppressor for the secY24(Ts) mutant (31). The ssyA3 mutation restored the defect in protein secretion caused by the secY24 mutation (33) and rescued the temperature-sensitive cell growth of secY24 mutant cells. The ssyA3 mutation caused cold-sensitive cell growth by itself and impaired protein synthesis was observed in the ssyA3 mutant at low temperatures (31). The cold-sensitive growth of the ssyA3 mutant was rescued by introduction of the wild-type copy of suhB, indicating that ssyA3 is a mutant allele of suhB (40). The suhB2(Cs) mutation is another allele of suhB and was isolated as an extragenic suppressor of the rpoH15(Ts) mutation. The rpoH15 mutant gene produces an altered 32 protein and causes a defect in the induction of heat shock proteins at higher temperatures (42). The suhB2(Cs) mutation rescued the temperature-sensitive cell growth of the rpoH15 mutant and partially restored heat shock induction in the mutant cell (40). A coldsensitive mutation was also mapped in the suhB locus as an extragenic suppressor for the dnaB121(Ts) mutation that inhibits replication of phage (2). Thus, mutant alleles of suhB have effects on diverse cell activities, including protein export, stress response, and DNA replication.The suhB gene encodes a protein of 268 amino acids (40), and the primary structure of its translated product shows a high level of similarity t...

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Section: Resultsmentioning

confidence: 99%

Inositol monophosphatase activity from the Escherichia coli suhB gene product

et al. 1995

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“…In the experiments where the effect of Li+ was investigated, 5 X lo-' moL4 LiCl or 5X moVl NaCl in control incubations was included from the sedimentation step onwards on the second day. Li+ uncompetitively inhibits inositol-I-phosphatase from rat brain and inositol polyphosphate Iphosphatase from calf brain with 50% inhibition at 1-6X mol/ 1 (Takimoto et al 1985;Inhorn & Majerus 1987), indicating that 5X mol/l Li+ should inhibit substantially the degradation of inositol phosphates.…”

Section: Methodsmentioning

confidence: 99%

Effect of Concomitant β‐Adrenoceptor Stimulation on α₁‐Adrenoceptor‐Mediated Increase of Inositol‐1, 4, 5‐trisphosphate Mass in Adult Rat Cardiomyocytes

Viko¹,

Sandnes²,

Skomedal³

et al. 1998

Pharmacology & Toxicology

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Abstract:The aim of the present study was to investigate the accumulation of inositol-l,4,5-trisphosphate (IP,) in isolated adult rat ventricular cardiomyocytes after a,-and P-adrenoceptor stimulation, separate and in combination, in order to elucidate a possible influence of concomitant P-adrenoceptor stirnulation on the al-adrenoceptor stimulated response. IP3 was measured by a radioligand binding assay based on an (1,4,5)IP3-specific binding protein from bovine adrenal cortex. The basal IP, content was 4.06?0.31 pmol/mg protein (N=56). a,-Adrenoceptor stimulation resulted in a rapid increase in the IP3 level, which reached a plateau, 50-80% above basal level, at 10-30 sec. The plateau lasted at least up to 120 sec., while at 300 sec. there was no significant difference between control values and values after a,-adrenoceptor stimulation. Li+ did not affect either the basal IP3 level, or the magnitude or time course of al-adrenoceptor-stimulated IP, accumulation. Combined adrenoceptor stimulation gave a similar response as separate al-adrenoceptor stimulation, whereas there was no significant change in the IP, level after P-adrenoceptor stimulation. No inhibitory influence of simultaneous P-adrenoceptor stimulation on the al-adrenoceptor-stimulated increase of IP3 mass was revealed.The existence of both a l -and P-adrenoceptors in rat myocardium is well established (Osnes et al. 1985;Terzic et al. 1993). al-Adrenoceptor stimulation activates phospholipase C, resulting in breakdown of phosphoinositide 4,5-bisphosphate to inositol-1,4,5-trisphosphate (IP3) and diacylglycer-01. IP, releases Ca2+ from internal stores in most cell types, and diacylglycerol activates protein kinase C (Terzic et al. 1993). Whereas protein kinase C has been implicated in the al-adrenergic inotropic effect (Terzic et al. 1993), and in the regulation of cardiac growth (Sugden & Bogoyevitch 1995), the physiological role of IP3 in the heart remains unclear, since a clearcut effect on Ca*+-release has not been found (Terzic et al. 1993).When al-adrenoceptors are stimulated under physiological conditions, P-adrenoceptors are activated simultaneously. An inhibitory influence of concomitant P-adrenoceptor stimulation has been reported for several q-adrenoceptor-mediated responses in the myocardium. At the functional level, the al-adrenoceptor-stimulated inotropic response was attenuated by 0-adrenoceptor stimulation (Skomedal et al. 1988; Osnes et af. 1989). The a,-adrenoceptor-stimulated increase in potassium uptake rate of isolated ventricular cardiomyocytes was also attenuated by concomitant P-adrenoceptor stimulation (Viko et al. 1996). However, when myocardial phospholipase C activity was determined after labelling of cells with radioactive inositol (Berridge & Irvine 1989), simultaneous P-adrenoceptor stimulation either inhibited (Guse et al. 1991) Changes in labelled inositol phosphates may not reflect regulation of the IP3 mass, and thus a possible mediator function of IP3. Generation of inositol phosphates may occur independently of...

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“…The other major reason for the interest in this enzyme is that it is inhibited by Li' (Naccarato et al, 1974;Hallcher & Sherman, 1980;Takimoto et al, 1985). This -inhibition is interesting since it has been found that Li+, which is widely used in the treatment of manic depression, causes a rise in the cortical concentration of InsI-P in rat brain on both acute (Allison et al, 1976) and chronic (Sherman et al, 1981) treatment.…”

Section: Introductionmentioning

confidence: 99%

“…This -inhibition is interesting since it has been found that Li+, which is widely used in the treatment of manic depression, causes a rise in the cortical concentration of InsI-P in rat brain on both acute (Allison et al, 1976) and chronic (Sherman et al, 1981) treatment. Takimoto et al (1985) have purified the rat brain myoinositol-l-phosphatase and have reported some of its properties. Most of the work on the bovine enzyme reported to date has been performed on fairly crude enzyme preparations from bovine brain, with specific activities of about 45 units (1 unit corresponds to release of 1 /tmol of P,/h at 37°C)/mg (Hallcher & Sherman, 1980;Ackerman et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Purification and properties of myo-inositol-1-phosphatase from bovine brain

Attwood¹,

Ducep²,

Chanal³

1988

Biochemical Journal

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myo-Inositol-1-phosphatase from bovine brain was purified over 2000-fold. The native enzyme has a Mr of 59,000, and on SDS/polyacrylamide-gel electrophoresis the subunit Mr was 31,000. Thus the native enzyme is a dimer of two apparently identical subunits. The enzyme, purified to a specific activity of more than 300 units/mg of protein (1 unit of enzyme activity corresponds to the release of 1 mumol of Pi/h at 37 degrees C), catalysed the hydrolysis of a variety of phosphorylated compounds, the best one, in terms of V/Km, being D-myo-inositol 1-phosphate. Kinetic constants of compounds tested, including both isomers of glycerophosphate and two deoxy forms of beta-glycerophosphate, were measured. They show the importance of the two hydroxyl groups which are adjacent to the phosphate in myo-inositol 1-phosphate. With a wide variety of substrates Li+ was found to be an uncompetitive inhibitor whose Ki varied with substrate structure.

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Purification and Properties of myo-Inositol-1-Phosphatase from Rat Brain

Cited by 87 publications

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Inositol monophosphatase activity from the Escherichia coli suhB gene product

Inositol monophosphatase activity from the Escherichia coli suhB gene product

Effect of Concomitant β‐Adrenoceptor Stimulation on α₁‐Adrenoceptor‐Mediated Increase of Inositol‐1, 4, 5‐trisphosphate Mass in Adult Rat Cardiomyocytes

Purification and properties of myo-inositol-1-phosphatase from bovine brain

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Purification and Properties of myo-Inositol-1-Phosphatase from Rat Brain

Cited by 87 publications

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Inositol monophosphatase activity from the Escherichia coli suhB gene product

Inositol monophosphatase activity from the Escherichia coli suhB gene product

Effect of Concomitant β‐Adrenoceptor Stimulation on α1‐Adrenoceptor‐Mediated Increase of Inositol‐1, 4, 5‐trisphosphate Mass in Adult Rat Cardiomyocytes

Purification and properties of myo-inositol-1-phosphatase from bovine brain

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Effect of Concomitant β‐Adrenoceptor Stimulation on α₁‐Adrenoceptor‐Mediated Increase of Inositol‐1, 4, 5‐trisphosphate Mass in Adult Rat Cardiomyocytes