Inositol formation by cyclization of glucose chain in rat testis

Eisenberg, Frank; Bolden, Arthur H.; Loewus, Frank A.

doi:10.1016/0006-291x(64)90079-8

Cited by 62 publications

(26 citation statements)

References 13 publications

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“…D- [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]Glucose 6-phosphate (specific activity, 60.3 mCi/mmol) and [1,[2][3] H]myo-inositol (specific activity, 370 -740 GBq/mmol) were obtained from DuPont NEN. Glucose 6-phosphate, bacterial alkaline phosphatase, and phosphate standard were purchased from Sigma.…”

Section: Methodsmentioning

confidence: 99%

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Differentially Expressed Forms of 1-L- -Inositol-1-Phosphate Synthase (EC) in

Johnson

Wang

1996

Journal of Biological Chemistry

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We have characterized two distinct polypeptides with 1-L-myo-inositol-1-phosphate synthase (MI-1-P synthase) activity that are differentially expressed during development in Phaseolus vulgaris. Western analyses, enzyme assays, and partial purification of MI-1-P synthase during embryonic and postembryonic development show that its expression is temporally and spatially regulated.Developmental Western analyses of soluble proteins detect a small protein, approximately 33 kDa, with MI-1-P synthase activity during the globular stage (stage II) of embryogenesis and in mature roots. Expression of this small protein is also enriched in thylakoidal membranes of fractionated leaf chloroplasts, although Western analyses of total soluble leaf proteins show no crossreacting material. In contrast, a larger protein, approximately 56 kDa, with MI-1-P synthase activity is present during the cotyledonary phase (stage IV) of embryogenesis in green cotyledons of seedlings and in young roots.

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Section: Methodsmentioning

confidence: 99%

“…Inositol 1-phosphate, the immediate precursor of free inositol, is synthesized via an internal cyclization of glucose 6-phosphate (5)(6)(7)(8). The enzyme that catalyzes this reaction, MI-1-P synthase, 1 has been purified or partially purified from a number of organisms (9 -12).…”

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confidence: 99%

Differentially Expressed Forms of 1-L- -Inositol-1-Phosphate Synthase (EC) in

Johnson

Wang

1996

Journal of Biological Chemistry

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“…The rate-limiting step of myo-inositol synthesis is catalyzed by L-myo-inositol 1-phosphate synthase (MIPS; EC 5.5.1.4) (Eisenberg et al, 1964;Loewus et al, , 1984Gumber et al, 1984). This reaction is followed by dephosphorylation of L-myo-inositol 1-phosphate to myoinositol, which is catalyzed by the myo-inositol monophosphatase (IMP; EC 3.1.3.25) (Sherman et al, 1981;Loewus and Loewus, 1983;Torabinejad and Gillaspy, 2006;Torabinejad et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

TheArabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required forMyo-inositol Synthesis and Suppression of Cell Death

et al. 2010

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L-myo-inositol 1-phosphate synthase (MIPS; EC 5.5.1.4) catalyzes the rate-limiting step in the synthesis of myo-inositol, a critical compound in the cell. Plants contain multiple MIPS genes, which encode highly similar enzymes. We characterized the expression patterns of the three MIPS genes in Arabidopsis thaliana and found that MIPS1 is expressed in most cell types and developmental stages, while MIPS2 and MIPS3 are mainly restricted to vascular or related tissues. MIPS1, but not MIPS2 or MIPS3, is required for seed development, for physiological responses to salt and abscisic acid, and to suppress cell death. Specifically, a loss in MIPS1 resulted in smaller plants with curly leaves and spontaneous production of lesions. The mips1 mutants have lower myo-inositol, ascorbic acid, and phosphatidylinositol levels, while basal levels of inositol (1,4,5)P 3 are not altered in mips1 mutants. Furthermore, mips1 mutants exhibited elevated levels of ceramides, sphingolipid precursors associated with cell death, and were complemented by a MIPS1-green fluorescent protein (GFP) fusion construct. MIPS1-, MIPS2-, and MIPS3-GFP each localized to the cytoplasm. Thus, MIPS1 has a significant impact on myo-inositol levels that is critical for maintaining levels of ascorbic acid, phosphatidylinositol, and ceramides that regulate growth, development, and cell death.

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“…Although organisms incorporate myoinositol into various compounds, there is only one biosynthetic route to produce myoinositol in what has been referred to as the Loewus pathway (Eisenberg et al, 1964;Chen and Charalampous, 1966;Sherman et al, 1969;. The conversion of Glc-6-P to InsP is catalyzed by the myoinositol phosphate synthase (EC 5.5.1.4; for review, see GhoshDastidar et al, 2006).…”

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confidence: 99%

VTC4 Is a Bifunctional Enzyme That Affects Myoinositol and Ascorbate Biosynthesis in Plants

et al. 2009

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Myoinositol synthesis and catabolism are crucial in many multiceullar eukaryotes for the production of phosphatidylinositol signaling molecules, glycerophosphoinositide membrane anchors, cell wall pectic noncellulosic polysaccharides, and several other molecules including ascorbate. Myoinositol monophosphatase (IMP) is a major enzyme required for the synthesis of myoinositol and the breakdown of myoinositol (1,4,5)trisphosphate, a potent second messenger involved in many biological activities. It has been shown that the VTC4 enzyme from kiwifruit (Actinidia deliciosa) has similarity to IMP and can hydrolyze L-galactose 1-phosphate (L-Gal 1-P), suggesting that this enzyme may be bifunctional and linked with two potential pathways of plant ascorbate synthesis. We describe here the kinetic comparison of the Arabidopsis (Arabidopsis thaliana) recombinant VTC4 with D-myoinositol 3-phosphate (D-Ins 3-P) and L-Gal 1-P. Purified VTC4 has only a small difference in the V max /K m for L-Gal 1-P as compared with D-Ins 3-P and can utilize other related substrates. Inhibition by either Ca 2+ or Li + , known to disrupt cell signaling, was the same with both L-Gal 1-P and D-Ins 3-P. To determine whether the VTC4 gene impacts myoinositol synthesis in Arabidopsis, we isolated T-DNA knockout lines of VTC4 that exhibit small perturbations in abscisic acid, salt, and cold responses. Analysis of metabolite levels in vtc4 mutants showed that less myoinositol and ascorbate accumulate in these mutants. Therefore, VTC4 is a bifunctional enzyme that impacts both myoinositol and ascorbate synthesis pathways.

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Inositol formation by cyclization of glucose chain in rat testis

Cited by 62 publications

References 13 publications

Differentially Expressed Forms of 1-L- -Inositol-1-Phosphate Synthase (EC) in

Differentially Expressed Forms of 1-L- -Inositol-1-Phosphate Synthase (EC) in

TheArabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required forMyo-inositol Synthesis and Suppression of Cell Death

VTC4 Is a Bifunctional Enzyme That Affects Myoinositol and Ascorbate Biosynthesis in Plants

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