Contributions in astrocytes of SMIT1/2 and HMIT to myo-inositol uptake at different concentrations and pH

2012 ◽  
Vol 61 (2) ◽  
pp. 187-194 ◽  
Author(s):  
Hui Fu ◽  
Baoman Li ◽  
Leif Hertz ◽  
Liang Peng
Keyword(s):  
Inositol Uptake

Inositol Transport by Hepatopancreatic Brush-Border Membrane Vesicles of the Lobster Homarus Americanus

1988 ◽  
Vol 140 (1) ◽  
pp. 107-121
Author(s):  
TEVA SIU ◽  
GREGORY A. AHEARN
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Homarus Americanus ◽  
Brush Border Membrane Vesicles ◽  
Carrier Mechanism ◽  
Apparent Diffusion ◽  
Noncompetitive Inhibitor ◽  
Inositol Uptake ◽  
Glucose Carrier

The mechanism of [3H]myo-inositol transport by the lobster hepatopancreas was examined using purified brush-border membrane vesicles. Transport was stimulated by a 100 mmoll−1 inward Na+ gradient, but other cation gradients were ineffective, suggesting a Na+-dependent transfer mechanism. The transport system was most efficient at pH7.0 (both sides), rather than in the presence of a pH gradient (pHin = 7.0; pHout = 5.5) or at bilaterally low pH (pHin = pHout = 5.5). The system was shown to be electrogenic in two different ways. First, myo-inositol uptake was stimulated by anions of increasing permeability (SCN− > Cl− > gluconate). Second, an outwardly directed, valinomycin-induced K+ diffusion potential (inside negative) enhanced uptake in comparison with vesicles lacking the ionophore. Myo-inositol was transported by a carrier mechanism with an apparent Kt of 0.79mmoll−1, a Jmax of 6.3pmolmg protein−1 s−1, and by apparent diffusion with a permeability coefficient of 5.92 pmolmg protein−1s−1 (mmolT1)−1. D-Glucose was a noncompetitive inhibitor of myo-inositol uptake, but myo-inositol did not significantly reduce the transport of D-[3H]glucose. Vesicles preloaded with myo-inositol trans-stimulated [3H]myo-inositol uptake, whereas those preloaded with D-glucose did not, suggesting that the inositol carrier did not transport D-glucose. It is proposed that myo-inositol does not share the glucose carrier, and that D-glucose may modulateinositol influx by binding to a ‘regulator’ site on the inositol carrier.

scholarly journals Identification of Two myo-Inositol Transporter Genes of Bacillus subtilis

2002 ◽  
Vol 184 (4) ◽  
pp. 983-991 ◽  
Author(s):  
Ken-Ichi Yoshida ◽  
Yoshiyuki Yamamoto ◽  
Kaoru Omae ◽  
Mami Yamamoto ◽  
Yasutaro Fujita
Keyword(s):  
Bacillus Subtilis ◽  
Promoter Region ◽  
Genome Project ◽  
Growth Defect ◽  
Promoter Regions ◽  
Significant Similarity ◽  
Sugar Transporters ◽  
Dnase I Footprinting ◽  
Inositol Uptake

ABSTRACT Among hundreds of mutants constructed systematically by the Japanese groups participating in the functional analysis of the Bacillus subtilis genome project, we found that a mutant with inactivation of iolT (ydjK) exhibited a growth defect on myo-inositol as the sole carbon source. The putative product of iolT exhibits significant similarity with many bacterial sugar transporters in the databases. In B. subtilis, the iolABCDEFGHIJ and iolRS operons are known to be involved in inositol utilization, and its transcription is regulated by the IolR repressor and induced by inositol. Among the iol genes, iolF was predicted to encode an inositol transporter. Inactivation of iolF alone did not cause such an obvious growth defect on inositol as the iolT inactivation, while simultaneous inactivation of the two genes led to a more severe defect than the single iolT inactivation. Determination of inositol uptake by the mutants revealed that iolT inactivation almost completely abolished uptake, but uptake by IolF itself was slightly detectable. These results, as well as the Km and V max values for the IolT and IolF inositol transporters, indicated that iolT and iolF encode major and minor inositol transporters, respectively. Northern and primer extension analyses of iolT transcription revealed that the gene is monocistronically transcribed from a promoter likely recognized by ςsgr;A RNA polymerase and negatively regulated by IolR as well. The interaction between IolR and the iolT promoter region was analyzed by means of gel retardation and DNase I footprinting experiments, it being suggested that the mode of interaction is quite similar to that found for the promoter regions of the iol divergon.

scholarly journals The uptake of 3H-labelled monodeoxyfluoro-myo-inositols into thymocytes and their incorporation into phospholipid in permeabilized cells

1993 ◽  
Vol 291 (2) ◽  
pp. 553-560 ◽  
Author(s):  
J Offer ◽  
J C Metcalfe ◽  
G A Smith
Keyword(s):  
Cellular Responses ◽  
Effective Inhibitor ◽  
Permeabilized Cells ◽  
Label Technique ◽  
Competitive Inhibitors ◽  
Phosphatidylinositol Synthase ◽  
Potential Inhibitors ◽  
Dual Label ◽  
Inositol Uptake

Monodeoxyfluoro-myo-inositols were applied to electropermeabilized and intact thymocyte preparations to study their metabolism and uptake in order to investigate their suitability as potential inhibitors of phosphoinositide-mediated cellular responses. Only three of the monodeoxyfluoro-myo-inositols were incorporated into the phospholipids of thymocytes: 1D-3-deoxy-3-fluoro-myo-inositol, 5-deoxy-5-fluoro-myo-inositol and 1D-6-deoxy-6-fluoro-myo-inositol, all of which were weaker substrates for phosphatidylinositol synthase than was myo-inositol. The 3-, 5- and 6-fluoro analogues also behaved as competitive inhibitors, with K1 values of 350 +/- 5 microM, 350 +/- 5 microM and 2.9 +/- 2 mM respectively, compared with a Km for myo-inositol of 31 +/- 4 microM. When incubated with electropermeabilized thymocyte preparations, these three analogues of myo-inositol all formed phospholipids with chromatographic properties which corresponded to those of substituted phosphatidylinositol and phosphatidylinositol monophosphate. The uptake of myo-inositol and of the monodeoxyfluoro-myo-inositols into intact thymocytes was studied by a dual-label technique. All the monodeoxyfluoro-myo-inositols were taken up to some extent, but only 2-deoxy-2-fluoro-myo-inositol and 1D-3-deoxy-3-fluoro-myo-inositol were actively concentrated. The monodeoxyfluoro-myo-inositols were also assayed for their ability to inhibit the uptake of myo-inositol into cells. Both 2-deoxy-2-fluoro-myo-inositol and 1D-3-deoxy-3-fluoro-myo-inositol were effective inhibitors of myo-inositol uptake. Furthermore, 1D-1-deoxy-1-fluoro-myo-inositol, which was not taken up actively, was an effective inhibitor of myo-inositol uptake. The three effective inhibitors all showed Ki values of approximately 150 microM, close to the apparent Km for inositol uptake of 180 microM, and the 4-, 5- and 6-fluoro analogues had Ki values in excess of 10 mM.

Retinoic acid treatment of fibroblasts causes a rapid decrease in [3H]inositol uptake

1989 ◽  
Vol 181 (2) ◽  
pp. 385-399 ◽  
Author(s):  
Rashmi Sinha ◽  
Kim E. Creek ◽  
Carol Silverman-Jones ◽  
Luigi M. de Luca
Keyword(s):  
Retinoic Acid ◽  
Acid Treatment ◽  
Rapid Decrease ◽  
Retinoic Acid Treatment ◽  
Inositol Uptake

Effect of prolactin on inositol uptake in mouse mammary gland explants

Endocrine ◽  
2007 ◽  
Vol 31 (1) ◽  
pp. 27-32
Author(s):  
James A. Rillema ◽  
Charles A. Bell
Keyword(s):  
Mammary Gland ◽  
Mouse Mammary Gland ◽  
Inositol Uptake

Eicosapentaenoic acid enhances myo-inositol uptake in cultured human aortic smooth muscle cells

Life Sciences ◽  
1994 ◽  
Vol 55 (1) ◽  
pp. PL15-PL18 ◽  
Author(s):  
Yukichi Okuda ◽  
Motomi Ezure ◽  
Toshie Sawada ◽  
Masakazu Mizutani ◽  
Kenichiro Tsukahara ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Eicosapentaenoic Acid ◽  
Muscle Cells ◽  
Aortic Smooth Muscle Cells ◽  
Aortic Smooth Muscle ◽  
Inositol Uptake

Osmotic regulation of Na-myo-inositol cotransporter mRNA level and activity in endothelial and neural cells

1996 ◽  
Vol 271 (3) ◽  
pp. 2-2 ◽  
Author(s):  
T. J. Wiese ◽  
J. A. Dunlap ◽  
C. E. Conner ◽  
J. A. Grzybowski ◽  
W. L. Lowe ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Osmotic Shock ◽  
Mrna Level ◽  
Cdna Probe ◽  
Lens Epithelial Cells ◽  
Neural Cells ◽  
Osmotic Regulation ◽  
Accession Number ◽  
Hand Column ◽  
Inositol Uptake

Pages C990-C997: T. J. Wiese, J. A. Dunlap, C. E. Conner, J. A. Grzybowski, W. L. Lowe, Jr., and M. A. Yorek. “Osmotic regulation of Na- myo-inositol cotransporter mRNA level and activity in endothelial and neural cells.” Page C994, right-hand column, line 4: the statement that reads “BAE cells were not examined because a cDNA probe for the bovine SMIT gene was not available” is erroneous, because a paper was published in 1994 by C. Zhou, N. Agarwal, and P. R. Cammarata (Invest. Ophthalmol. Visual Sci. 35: 1236-1242, 1994) entitled “Osmoregulatory alterations in myo-inositol uptake by bovine lens epithelial cells. Part 2: cloning of a 626 bp cDNA portion of a Na+/myo-inositol cotransporter, an osmotic shock protein.” The GenBank accession number of that bovine Na-myo-inositol cotransporter cDNA is S72877.

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